Spinal Fixation System

ABSTRACT

A spinal fixation system includes an expandable disc replacement body and an adjustment mechanism. The expandable disc replacement body includes a first wall, a second wall, a hinge connecting the first wall and the second wall, and a first bone-screw receiving section at a proximal end of the first wall. The adjustment mechanism is positioned between the first wall and the second wall, and an angle between the first wall and the second wall can be varied by movement of the adjustment mechanism.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/331,706, filed Mar. 8, 2019, which is a 371 U.S. National Phaseapplication of PCT/US17/50775, filed Sep. 8, 2017, which claims priorityto U.S. Patent Application No. 62/384,972 filed Sep. 8, 2016.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a fixation system for orthopedic orneurological surgery on a patient, and more particularly to a fixationsystem for anterior or lateral spine surgery, in which the primaryintention is to fuse the spine.

2. Description of the Related Art

As an example, the most common method for surgically decompressingspinal cord or spinal nerve root compression at the level of thecervical spine is a procedure known as an anterior cervical discectomyand fusion. This procedure has been used successfully with minimalchange in technique for several decades. Similar anterior and directlateral approaches to the spine can be used to treat spinal disease atthe thoracic, lumbar and lumbo-sacral levels as well. The currentstandard is that a piece of bone or a cage is placed into the disc spacefollowing discectomy, and a plate is then placed over the top of thedisc space connecting the bone above and below the disc space via bonescrews inserted through openings in the plate. The end goal is to havethese two bones grow into one, which is called a fusion. This biologicalprocess is significantly enhanced by the rigidity added by the platefixation and the biological substrate added by the bone or cage (whichis filled with bone growth enhancing materials).

Recently, the functions of a plate and a cage have combined in devicesthat may be called screw-cages. However, these screw-cages providesuboptimal rigidity (especially in weakened bone) and the screws take upspace that could be used to achieve a biological fusion. Furthermore,these devices are largely mono-block in nature, which limits theirability to conform to or change the shape of the space in which they areplaced as well as preventing the ability to directly compress the bonegraft between the endplates of the vertebrae being fused. It is wellknown to those versed in the art that bone heals best in compression,according to Wolff's Law. Thus, an ideal device would be one that canencourage compression on the graft. Current devices do not possess theability to directly compress the bone graft between the endplates of thevertebrae being fused.

What is needed therefore is a spinal fixation system that would addressthese shortcomings.

SUMMARY OF THE INVENTION

The present invention addresses the foregoing needs by providing spinalfixation systems, multi-level spinal fixation systems, and kits forspinal surgery.

In one embodiment, the present disclosure provides a spinal fixationsystem comprising an expandable disc replacement body including a firstwall, a second wall, a hinge connecting the first wall and the secondwall; a first bone-screw receiving section at a proximal end of thefirst wall; and an adjustment mechanism positioned between the firstwall and the second wall, wherein an angle between the first wall andthe second wall can be continuously varied between a lower value of theangle and an upper value of the angle by movement of the adjustmentmechanism. The expandable disc replacement body may include a secondbone-screw receiving section at a proximal end of the second wall.

In one aspect of this embodiment, the first bone-screw receiving sectionhas a first opening for receiving a first bone screw, the first openinghaving a first longitudinal axis, and the first bone-screw receivingsection may have a second opening for receiving a second bone screw, thesecond opening having a second longitudinal axis, and wherein the firstlongitudinal axis and the second longitudinal axis diverge in adirection toward a distal end of the expandable disc replacement body.The first bone-screw receiving section may have a first recessed edgebetween the first opening and the second opening. The first bone-screwreceiving section may also have a first grasping recess between thefirst opening and the second opening. The second bone-screw receivingsection may have a third opening for receiving a third bone screw, thethird opening having a third longitudinal axis, and the secondbone-screw receiving section may have a fourth opening for receiving afourth bone screw, the fourth opening having a fourth longitudinal axis,and wherein the third longitudinal axis and the fourth longitudinal axisdiverge in a direction toward a distal end of the expandable discreplacement body.

In another aspect of this embodiment, the adjustment mechanism comprisesa first wedge which slidably engages the first and second walls. Thefirst wedge may include a first wedge screw aperture for receiving afirst wedge translating screw which is threadably connected to a firstinternally threaded cylinder that is directly coupled to the hinge ofthe expandable disc replacement body. The first wedge screw aperture mayinclude a first wedge snap ring recess containing a first wedge snapring. When the first wedge translating screw is received within thefirst wedge screw aperture, the first wedge snap ring may expand intothe first wedge snap ring recess to allow entry of the first wedgetranslating screw and if the first wedge translating screw passes thefirst wedge snap ring, the first wedge snap ring may contract,effectively blocking the first wedge translating screw from backing out.

If the first wedge translating screw is rotated, the rotation maycorrelate to a predetermined change in the angle between the first andsecond walls. The adjustment mechanism may further comprise a secondwedge which slidably engages the first and second walls. The first wedgeand the second wedge may be inserted in unequal amounts to make a firstadjustment angle between the first wall and the second wall on onelateral side of the expandable disc replacement body different than asecond adjustment angle between the first wall and the second wall onanother lateral side of the expandable disc replacement body. Ananterior plate cover may be detachably coupled to the proximal end ofthe first wall. A disc replacement holder including four angled drillguide holes and a grasping mechanism may be detachably coupled to thegrasping recess of the first wall.

In yet another aspect of this embodiment, the first opening includes afirst snap ring recess containing a first snap ring, and the secondopening may include a second snap ring recess containing a second snapring. When the first bone screw is received within the first opening,the first snap ring may expand into the first snap ring recess to allowentry of the first bone screw and once the first bone screw passes thefirst snap ring, the first snap ring may contract, effectively blockingthe first bone screw from backing out, and when the second bone screw isreceived within the second opening, the second snap ring may expand intothe second snap ring recess to allow entry of the second bone screw andonce the second bone screw passes the second snap ring, the second snapring may contract, effectively blocking the second bone screw frombacking out.

Additionally, the third opening may include a third snap ring recesscontaining a third snap ring, and the fourth opening may include afourth snap ring recess containing a fourth snap ring. When the thirdbone screw is received within the third opening, the third snap ring mayexpand into the third snap ring recess to allow entry of the third bonescrew and once the third bone screw passes the third snap ring, thethird snap ring may contract, effectively blocking the third bone screwfrom backing out, and when the fourth bone screw is received within thefourth opening, the fourth snap ring may expand into the fourth snapring recess to allow entry of the fourth bone screw and once the fourthbone screw passes the fourth snap ring, the fourth snap ring maycontract, effectively blocking the fourth bone screw from backing out.

In still another aspect of this embodiment, the first wall has a firstspace to allow for insertion of bone graft, and the second wall may havea second space to allow for insertion of bone graft. The hinge may beformed by a pliable material coupling the first wall and the secondwall. The first wall and the second wall may each include a fixationanchor for engaging a vertebra.

In a further aspect of this embodiment, the adjustment mechanismcomprises a scissor jack which engages the first and second walls. Theadjustment mechanism may comprise a scissor jack having an anteriorlyaccessible lead screw, and when the lead screw is rotated, the rotationmay correlate to a predetermined change in the angle between the firstand second walls. The adjustment mechanism may comprise a scissor jackhaving a posteriorly accessible lead screw, and when the lead screw isrotated, the rotation may correlate to a predetermined change in theangle between the first and second walls.

In a still further aspect of this embodiment, the adjustment mechanismcomprises a feedback device for indicating an increment of movement ofthe adjustment mechanism. The feedback device may be a tactile device.The feedback device may be a display device. At least one of the firstwall and the second wall may include a contoured bone engaging surface.At least one of the first wall and the second wall may includeperforations.

In an even further aspect of this design, the hinge comprises a pair ofarcuate structures, a pair of cylindrical structures, one of the pair ofarcuate structures surrounding one of the pair of cylindricalstructures, the other of the pair of arcuate structures surrounding theother of the pair of cylindrical structures, wherein the pair of arcuatestructures is connected to at least one of the first wall and the secondwall, and wherein the pair of cylindrical structures is connected to theother of the first wall and the second wall. An arcuate length of atleast one of the pair of arcuate structures may be used to limit theupper value of the angle by contacting one of the first wall and thesecond wall. The first wall may have a first space to allow forinsertion of bone graft, and the hinge may comprise a bar connecting thepair of arcuate structures or the pair of cylindrical structures. Thebar may be convex on a side facing the first space.

The adjustment mechanism may comprise a first wedge which slidablyengages the first and second walls, wherein at least one of the firstwall and the second wall includes a channel, and wherein the first wedgeincludes a protrusion which extends into and is movable in the channel.Motion of the first wedge may be along an axis parallel to the secondwall.

The adjustment mechanism may comprise a first wedge which slidablyengages the first and second walls and a second wedge which slidablyengages the first and second walls, wherein one of the first wall andthe second wall includes a pair of channels, also wherein the firstwedge includes a protrusion which extends into and is movable in one ofthe pair of channels, and wherein the second wedge includes a protrusionwhich extends into and is movable in the other of the pair of channels.The first wedge and the second wedge may be located at opposite sides ofthe first and second walls.

The adjustment mechanism may include at least one threaded fastener incontact with threads in at least one of the first wall, second wall, thehinge, or the first wedge. The adjustment mechanism may comprise a firstwedge which slidably engages the first and second walls, wherein theadjustment mechanism includes a threaded fastener threadably connectedto an internally threaded hole of one of the pair of cylindricalstructures. The adjustment mechanism may include two threaded fastenerswhich can be inserted in unequal amounts to make a first adjustmentangle between the first wall and the second wall on one lateral side ofthe expandable disc replacement body different than a second adjustmentangle between the first wall and the second wall on another lateral sideof the expandable disc replacement body.

In another even further aspect of this embodiment, the adjustmentmechanism includes a locking component which prevents the adjustmentmechanism from changing the angle between the first wall and the secondwall when activated. The locking component may comprise a locking barcontacting the expandable disc replacement body which can be insertedinto the adjustment mechanism in order to prevent further rotationalmotion. The locking component may comprise a locking cap contacting theexpandable disc replacement body which surrounds the locking mechanismin order to prevent further rotational motion. The locking cap maycomprise at least one of teeth, one or more insertable posts, one ormore insertable spades, a square cover, a hex cover, or a torx cover forcontacting the locking mechanism.

In another embodiment, the present disclosure provides a spinal fixationsystem comprising a disc replacement body including a first wall and asecond wall and a plate including a pair of opposed flanges and a firstbone-screw receiving section at a superior end of the plate, wherein theopposed flanges are dimensioned to limit rotational movement of the discreplacement body when the plate is coupled to the disc replacement body.The plate may further include a second bone-screw receiving section atan inferior end of the plate. The first wall and the second wall may beangled such that a first distance between the first wall and the secondwall at a proximal end is larger than a second distance between thefirst wall and the second wall at a distal end. The first wall may havea first space to allow for insertion of bone graft, and the second wallmay have a second space to allow for insertion of bone graft.

In one aspect of this embodiment, the first bone-screw receiving sectionhas a first opening for receiving a first bone screw, the first openinghaving a first longitudinal axis, and the first bone-screw receivingsection has a second opening for receiving a second bone screw, thesecond opening having a second longitudinal axis and the firstlongitudinal axis, wherein the first longitudinal axis and the secondlongitudinal axis diverge in a direction toward a distal end of the discreplacement body.

In another aspect of this embodiment, the second bone-screw receivingsection has a third opening for receiving a third bone screw, the thirdopening having a third longitudinal axis, and the second bone-screwreceiving section has a fourth opening for receiving a fourth bonescrew, the fourth opening having a fourth longitudinal axis, wherein thethird longitudinal axis and the fourth longitudinal axis diverge in adirection toward a distal end of the disc replacement body.

In a further aspect of this embodiment the first bone-screw receivingsection has a first recessed edge between the first opening and thesecond opening and the second bone-screw receiving section has a secondrecessed edge between the third opening and the fourth opening. Theplate may be coupled to the disc replacement body by a screw locatedcentrally on the plate such that the plate is coupled to a proximal endof the disc replacement body. The pair of opposed flanges may be movableflanges, such that they can move towards each other and apart from oneanother. The plate may be coupled to the disc replacement body by themovable flanges of the plate grasping the disc replacement body suchthat the plate is coupled to a proximal end of the disc replacementbody.

In another embodiment, the present disclosure provides a spinal fixationsystem comprising a disc replacement body portion including a first walland a second wall, a plate portion including a first bone-screwreceiving section at a superior end of the plate portion, and a secondbone-screw receiving section at an inferior end of the plate portion,wherein the disc replacement body portion and the plate portion are aunitary component and are comprised of a material continuously formingthe disc replacement body portion and the plate portion.

In one aspect of this embodiment, the first bone-screw receiving sectionhas a first opening for receiving a first bone screw, the first openinghaving a first longitudinal axis, and the first bone-screw receivingsection has a second opening for receiving a second bone screw, thesecond opening having a second longitudinal axis, wherein the firstlongitudinal axis and the second longitudinal axis diverge in adirection toward a distal end of the disc replacement body portion.

In another aspect of this embodiment, the second bone-screw receivingsection has a third opening for receiving a third bone screw, the thirdopening having a third longitudinal axis, and the second bone-screwreceiving section has a fourth opening for receiving a fourth bonescrew, the fourth opening having a fourth longitudinal axis, wherein thethird longitudinal axis and the fourth longitudinal axis diverge in adirection toward a distal end of the disc replacement body portion.

In a further aspect of this embodiment, the first bone-screw receivingsection has a first recessed edge between the first opening and thesecond opening and the second bone-screw receiving section has a secondrecessed edge between the third opening and the fourth opening. Thefirst wall may have a first space to allow for insertion of bone graftand the second wall may have a second space to allow for insertion ofbone graft. The first wall and the second wall may be angled such that afirst distance between the first wall and the second wall at a proximalend is larger than a second distance between the first wall and thesecond wall at a distal end.

The embodiment may further comprise a wing having a stowed position inwhich the wing is within a perimeter of the disc replacement bodyportion and having a deployed position in which the wing extends beyondthe perimeter. The embodiment may comprise a second wing having a stowedposition in which the second wing is within a perimeter of the discreplacement body portion and having a deployed position in which thesecond wing extends beyond the perimeter.

In another embodiment, the present disclosure provides a spinal fixationsystem comprising a disc replacement body including a first wall, asecond wall, a joint connecting the first wall and the second wall andan adjustment mechanism positioned between the first wall and the secondwall, wherein an angle between the first wall and the second wall can bevaried by movement of the adjustment mechanism. The joint may be a balljoint.

In one aspect of this embodiment, the system further comprises aplurality of additional adjustment mechanisms positioned between thefirst wall and the second wall, wherein an angle between the first walland the second wall can be varied by movement of each additionaladjustment mechanism. The adjustment mechanism and each additionaladjustment mechanism may be located at corners of the disc replacementbody. The adjustment mechanism and each additional adjustment mechanismmay provide multi-planar disc space correction.

In another embodiment, the present disclosure provides a multi-levelspinal fixation system comprising a spinal fixation system as describedin any of the above embodiments, a second spinal fixation system asdescribed in any of the above embodiments, and a clamp dimensioned tocouple together the first spinal fixation system and the second spinalfixation system when the first spinal fixation system and the secondspinal fixation system are implanted in different intervertebral discspaces. In one aspect, the clamp includes an elliptical perimeter and anelongated slot, the clamp spatially fixing the first spinal fixationsystem relative to the second spinal fixation system.

In another embodiment, the present disclosure provides a kit for spinalsurgery comprising a plurality of disc replacement trial components,each of the disc replacement trial components comprising a bodyincluding a first wall and a second wall, a plate section including afirst bone-screw drill guide section at a superior end of the platesection, and a second bone-screw drill guide section at an inferior endof the plate section, wherein a first body of a first disc replacementtrial component of the plurality of disc replacement trial componentsand a second body of a second disc replacement trial component of theplurality of disc replacement trial components have different exteriordimensions.

In one aspect of this embodiment, the kit comprises a detachable handleconfigured to engage any of the plurality of disc replacement trialcomponents. A first angle between the first wall and the second wall ofthe first disc replacement trial component may be different than asecond angle between the first wall and the second wall of the seconddisc replacement trial component.

In another embodiment, the present disclosure provides a method forfixing adjacent vertebrae in a spine comprising obtaining a medicalimage of the spine, defining native dimensions of a disc space of thespine from the medical image, determining corrected dimensions for thedisc space of the spine, inserting a spinal fixation system as describedin any of the above embodiments in the disc space of the spine, andadjusting the angle between the first wall and the second wall bymovement of the adjustment mechanism such that the disc space of thespine corresponds to the corrected dimensions.

A spinal fixation system of the present disclosure allows a surgeon toaffix the cage or bone graft to the plate outside of the body, on theback operating room table, so that the cage and plate can be inserted ina single step, which would save time. In one embodiment, a spinalfixation system of the invention includes means for rigidly affixing thecage or bone graft to the plate, by having a central screw that can bethreaded through the plate and into the cage/bone. In an alternativeembodiment of the spinal fixation system, a double threaded screw isprovided. The double threaded screw includes one thread closing down twotransverse projections that pinch the cage/bone into place and a secondthread drives into the cage/bone. Cut-outs in the plate allow forplacement of distraction pins above and below the plate. Bends in theplate self-center the plate to provide optimal placement of the platewithout the need for radiographic guidance. In another embodiment of thespinal fixation system, a jig that is attached during insertionguarantees parallel, well placed screws with a convergent pattern, whichis the preferred trajectory.

In another embodiment of the spinal fixation system, the plate/cagedevice can be placed at multiple levels in a modular fashion, so thateach level has its own plate/cage device, instead of the current methodof placing one, difficult to fit, plate over the final construct. Thisalso means, that in the 25% of cases that require additional surgery,only one short plate needs to be removed, instead of exposing a longtraditional plate.

In another embodiment of the spinal fixation system, there is providedan adjustment mechanism for adjusting the lordosis (i.e., angulation) ofthe implant in-situ. With the plate-cage in place, one can turn a screwof the adjustment mechanism which then preferentially opens the anteriorportion of the plate (and/or cage), which will increase the lordosis.Each turn of the screw a specific number of degrees will provide a setamount of anterior height gain and therefore lordotic angulation (whichis trigonometrically determined). Correcting lost lordosis is a keyprincipal in anterior spine surgery and current art fails to achievethis goal.

In another embodiment of the spinal fixation system, an anterior coverplate can be optionally added to the plate system with customizablelordosis, this cover plate can act as a seal to the internal space, sothat demineralized bone matrix (DBM), bone chips and/or similar bonegrowth enhancing material can be contained in the cage. This cover platecan also be thicker to add additional structural support by acting as ananterior riser. This cover plate can snap into place around a flange orcan be screwed into place. It can have a central defect that can allowfor a syringe to connect to inject DBM or other bone growth stimulatingmaterial into the internal space of the cage. This defect can then becovered with a screw. The graft can be placed after the plate has itsfinal lordosis. The graft can slide into place or the graft can be loosepaste that is held into place with the cage.

In another embodiment of the spinal fixation system, pre-cut bone graftscan be machined to match the areal dimensions of the central defect inthe customizable lordosis plate system, and can be fabricated todifferent degrees of lordosis and constitutions of cortical vs.cancellous bone to be placed into the central defect as asemi-structural bone graft.

It is an advantage of the invention to provide a modular plate system.

It is another advantage of the invention to provide a modular plate thathas the ability to customize lordosis. In-situ lordosis correction as inthe present invention is gentler then malleting in hyperlordotic tapercages/grafts. Lordosis is a key sagittal parameter in spinal fusionsurgery. Every spinal fusion surgery is a “deformity” surgery. Bydefinition, spinal fusion surgery is intended to permanently eliminatemotion at a vertebral motion segment. Thus, every time you eliminate amotion segment, you reduce the spine's ability to compensate formalalignment, especially if that malalignment occurs iatrogenically dueto the fusion. Controlled, in-situ lordosis correction, allows forgentle application of corrective force. The device can be inserted in aparallel (planar) fashion, which is relatively small for the space andthen the lordosis adjustment mechanism can be engaged, to fill the spaceand ultimately correct the alignment, thereby improving the sagittalalignment of that segment of the spine. The fact that these adjustmentscan occur to such a great degree using the same base configuration atany level of the spine, means that a significantly fewer number ofdevices needed to be present to achieve the same number of finalgeometric configurations as compared to prior art which utilizesmono-block designs that cannot be in-situ custom corrected. Forinstance, in the cervical spine, a complete spinal kit could includethree basic width-depth dimension sizes that come in five posteriorhinge heights. Thus, fifteen total devices would be needed in the kit,but if each device can be custom adjusted, in-situ to 12 degrees oflordosis from a parallel base orientation, then these fifteen devicescould replace 180 mono-block devices that would be needed to have thesame degree of freedom in terms of final geometric configuration.

It is yet another advantage of the invention to provide a spinalfixation system that includes an adjustable plate/graft or plate/cageinterface so that a surgeon can use any company's graft or cage or onethat is machined specific for the system.

It is still another a advantage of the invention to provide a spinalfixation system that includes an insertion device which allows for thedrill guide and screws to be placed with one instrument, yieldingconsistent symmetry in screw placement and a one-step insertion of graftand fixation of the plate. In one embodiment, the custom jig forinserting the device, can include a torque-limited, single step screwdriver mechanism, that is branched. This allows the surgeon tosimultaneously adjust the lordosis producing mechanism located on bothsides of the device with a single turn of a screw driver during theinsertion step. In other embodiments, the screw driver can be astand-alone instrument, torque limited to prevent breaking the screwhead and/or the vertebral bone.

It is yet another advantage of the invention to provide a spinalfixation system with a plate having an anterior cut-out that allows theplate to be placed with a Caspar pin distractor still in place. As aresult, the plate/cage or plate/graft of the invention can be insertedwith distraction still being maintained. Many surgeons like the discspace to be distracted when the graft is placed in the traditionalmethod. Use of a Caspar pin distractor (most common method) may not bepossible without the anterior cut out of a plate of this embodiment ofthe spinal fixation system.

It is still another advantage of the invention to provide a spinalfixation system that has a low-profile and short cephalad/caudalextension, but still has definite flanges to prevent over-insertion.This facilitates corner screw placement (strongest bone, better angle ofattack) and maximum distance from adjacent levels. An example idealdistance is five millimeters from the adjacent level to minimize risk ofadjacent heterotopic ossification. This gives the best chance to placeabove a prior plate, without need for removal. In one embodiment, thebone screw holes are moved more centrally, to prevent the need for orgreatly diminish the length of an anterior flange on one or both sidesof the fixation device. This allows for the greatest ability to placethis device above an area of the spine which has previously beenoperated on.

It is yet another advantage of the invention to provide a spinalfixation system with disc replacement trial components that have thecorner lips, so they cannot be over inserted into the canal. The discreplacement trial components allow for accurate intraoperative templating of height, length and lordotic angle.

It is still another advantage of the invention to provide a spinalfixation system that has a modular design, that allows for smallerincisions, less magnitude of dissection and retraction. This canfacilitate a two (transverse) incision method for long constructs, whichmay lead to decreased dysphagia.

It is yet another advantage of the invention to provide a spinalfixation system with has a modular design that allows for level-specificlordosis correction. A surgeon can correct some levels more than others.

It is still another advantage of the invention to provide a spinalfixation system that achieves peripheral loading as the weight bearingload on the plate/graft is peripheral, where the bone is strongest.

It is yet another advantage of the invention to provide a spinalfixation system having a one-step insertion handle that allows for fixedangled and locked screw placement. Locking plates are the ideal meansfor fixating bone with a plate, especially of weakened quality. Alocking screw of the spinal fixation system can have threads in thescrew head that thread into the plate as they are inserted. Thisprevents screw stripping as well, since the locking screw threads limitprogression of the screw when the screw is fully engaged in the bone.Further, locked screws, make all screws one construct that has to failsimultaneous, as opposed to unlocked screws which can failedindividually, since they are not rigidly connected to the plate itself.

It is still another advantage of the invention to provide a spinalfixation system that allows for one-step insertion of the plate/cage orplate graft construct.

It is yet another advantage of the invention to provide a spinalfixation system with an elliptical ring that can be used to connectmodular plates in long constructs, where the concern is about the bonequality between plates (i.e., risk of pathologic fracture between twoadjacent plates).

It is still another advantage of the invention to provide a spinalfixation system that has the ability to directly compress the graft sothat the bones heal in compression.

It is yet another advantage of the invention to provide a spinalfixation system with in-situ, fully customizable lordosis correction(e.g., 12 degrees of angulation).

It is still another advantage of the invention to provide a spinalfixation system wherein each revolution of an adjustment screw equals aselected degree lordosis (e.g., 1 degree) with a palpable click.

It is yet another advantage of the invention to provide a spinalfixation system with a sturdy posterior hinge that sets disc spaceheight (e.g., 5 to 9 millimeters) and has various width/depth sizes(e.g., three sizes).

It is still another advantage of the invention to provide a spinalfixation system that has multiple configurations (e.g., fifteen)allowing for multiple different mono-block equivalents (e.g., onehundred eighty).

It is yet another advantage of the invention to provide a spinalfixation system with custom one-piece insertion instruments.

It is still another advantage of the invention to provide a spinalfixation system with a large central cavity for grafting.

It is yet another advantage of the invention to provide a spinalfixation system with direct compression applied to graft, e.g.,anti-kickout flange.

It is still another advantage of the invention to provide a spinalfixation system with an integrated screw-cage construct with low (e.g.,2.8 millimeters) anterior profile only at disc level. A two-partassembly is possible.

It is yet another advantage of the invention to provide a spinalfixation system that facilitates multi-level procedures, e.g.,Discectomy-Insert-Screw-Lordose-Graft-Done . . . Next.

It is still another advantage of the invention to provide a spinalfixation system with a vertical anterior overhang (e.g., 4millimeters)—excellent for adjacent segment degeneration (ASD) withflange-less options possible.

It is yet another advantage of the invention to provide a spinalfixation system with screw purchase in best (not worst) bone (e.g.,locking screws).

It is still another advantage of the invention to provide a spinalfixation system with sturdy titanium construction with bone-ingrowthsurface, which is an improvement over hydrophobic polyetheretherketone(PEEK) with resultant radiolucencies.

It is yet another advantage of the invention to provide a spinalfixation system with a custom allograft jig, i.e., one ten millimeterbone block can be used for all cases with lordosis cut to exactly matchin-situ correction, for ideal endplate effacement. Endplate effacementmeans that the end plates have good contact with the bone graft andpreferably this contact occurs with compression.

It is still another advantage of the invention to provide a spinalfixation system that is useable across the entire spine, both foranterior and lateral entry.

It is yet another advantage of the invention to have a large centralcavity that allows for placement of a large piece of bone (allograft orautograft) or bone healing material (like demineralized bone matrix) tobe placed in the central portion of the intervertebral place tofacilitate fusion. Unlike prior art which has placed the lordosisproducing mechanism and/or bone screw fixation holes in or near theselocations, thus reducing the space available for successful biologicalfusion, this invention maximizes the space available for fusion byplacing the lordosis producing mechanism on the sides of the device.This improvement over prior art increases the potential for solid bonyfusion, which is the successful end-state of a spinal fusion surgery.

It is yet another advantage of the invention to enable the ability todirectly compress the bone graft between the endplates of eachvertebrae, thus optimizing Wolff's Law. This device can be over-lordosedduring the insertion step, to allow for gentle placement of the bonegraft material centrally within the device and then the over-lordosiscan be reversed and in doing so apply compression to the graft.

It is yet another advantage of the invention that in a preferredembodiment is constructed from metal or metal alloys known to performwell when implanted in vivo. For instance, titanium alloys can be usedto fabricate the device and the surfaces of the upper and lower portionof the device that are directly opposed to the vertebral bone can becovered with bone in-growth encouraging preparations, like plasmasprayed particles. This allows for bony integration onto the device, inaddition to biological incorporation of the graft placed centrally.

These and other features, aspects, and advantages of the presentinvention will become better understood upon consideration of thefollowing detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view of a first embodiment of a spinalfixation system implanted on a spine.

FIG. 2 is a cross-sectional view of the spinal fixation system of FIG.1, taken along line 2-2 of FIG. 1.

FIG. 3 is a cross-sectional view of the spinal fixation system of FIG.1, taken along line 3-3 of FIG. 1.

FIG. 4A is similar to the cross-sectional view of the spinal fixationsystem of FIG. 1 shown in FIG. 2, but further includes a discreplacement holder.

FIG. 4B is a cross-sectional view of the disc replacement holder of FIG.4A, taken along line 4B-4B of FIG. 4A.

FIG. 4C is a cross-sectional view of the disc replacement holder of FIG.4A, taken along line 4C-4C of FIG. 4B.

FIG. 5 is an example embodiment of a bone screw received in an openingof a disc replacement body of the spinal fixation system of FIG. 1.

FIG. 6 is a top plan view of a snap ring shown in FIG. 6.

FIG. 7 is a front elevation view of a second embodiment of a spinalfixation system implanted on a spine.

FIG. 8 is a cross-sectional view of the spinal fixation system of FIG.7, taken along line 8-8 of FIG. 7, shown with a screw coupling a plateto a disc replacement body.

FIG. 9 is a top plan view of the spinal fixation system of FIG. 7.

FIG. 10A is a front elevation view of a third embodiment of a spinalfixation system implanted on a spine.

FIG. 10B is a side elevation view of the spinal fixation system of FIG.10A.

FIG. 11 is a top plan view of the spinal fixation system of FIG. 10A.

FIG. 12 is a side elevation view of the spinal fixation system of FIG.7, shown with a pair of movable flanges coupling a plate to a discreplacement body.

FIG. 13A is a front elevation view of the spinal fixation system of FIG.7, shown with a rack and pinion system in dashed lines.

FIG. 13B is a detail view of the rack and pinion system of FIG. 13A.

FIG. 14 is a front elevation view of a multi-level spinal fixationsystem implanted on a spine.

FIG. 15 is a side elevation view of a kit for spinal surgery.

FIG. 16 is a side elevation view of a fourth embodiment of a spinalfixation system implanted on a spine.

FIG. 17 is a side elevation view of a fifth embodiment of a spinalfixation system implanted on a spine.

FIG. 18 is a top plan view of a sixth embodiment of a spinal fixationsystem implanted on a spine, shown with deployable wings in a retractedposition.

FIG. 19 is a top plan view of the spinal fixation system of FIG. 18,shown with the deployable wings in an extended position.

FIG. 20 is a front elevation view of a seventh embodiment of a spinalfixation system.

FIG. 21 is a top plan view of the spinal fixation system of FIG. 20.

FIG. 22 is a front perspective view of an eighth embodiment of a spinalfixation system.

FIG. 23 is a top plan view of the spinal fixation system of FIG. 22.

FIG. 24 is an exploded perspective view of the spinal fixation system ofFIG. 22.

FIG. 25 is a side elevational view of the spinal fixation system of FIG.22.

FIG. 26 is a cross-sectional view of the spinal fixation system of FIG.22 taken along line 26-26 of FIG. 22.

FIG. 27 is a cross-sectional view of the spinal fixation system of FIG.22 taken along line 27-27 of FIG. 22.

FIG. 28A is a front partial perspective view of a screw lockingmechanism of a ninth embodiment of a spinal fixation system.

FIG. 28B is a rear partial perspective view of the screw lockingmechanism of FIG. 28A.

FIG. 29 is a front perspective view of a tenth embodiment of a spinalfixation system.

Like reference numerals will be used to refer to like parts from Figureto Figure in the following description of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Turning first to FIGS. 1-6, there is shown a first embodiment of aspinal fixation system 10 according to the invention implanted on aspine. The spinal fixation system 10 includes an expandable discreplacement body 12, an adjustment mechanism 14, and an anterior coverplate 16. The expandable disc replacement body 12 includes a first wall18, a second wall 20, a hinge 21 including a pin 22 attaching the firstwall 18 and the second wall 20 at a distal end 23 of the expandable discreplacement body 12, and two lateral sides 24. The disc replacement body12 may comprise a metallic material, such as titanium, cobalt chrome orstainless steel, a polymeric material, such as polyetheretherketone, ora ceramic material.

The first wall 18 of the expandable disc replacement body 12 includes afirst space 26 for receiving bone graft, such as allograft bone, and afirst bone-screw receiving section 28 located on a proximal end 30 ofthe first wall 18. The first bone-screw receiving section 28 includes afirst flange 31, a second flange 32, a first recessed edge 33 locatedbetween the first flange 31 and the second flange 32 on a superior edge34 of the first bone-screw receiving section 28, and a first graspingrecess 35 located between the first flange 31 and the second flange 32on an inferior edge 36 of the first bone-screw receiving section 28. Thefirst bone-screw receiving section 28 may angled back 3-5 degrees fromvertical to decrease the profile. The first flange 31 includes a firstopening recess 37, which surrounds a first opening 38. The second flange32 includes a second opening recess 39, which surrounds a second opening40. The first opening 38 defines a first longitudinal axis 41, and isconfigured to receive a first bone screw 42, and further includes afirst snap ring recess, which is configured to receive a first snapring. When the first bone screw 42 is received within the first opening38, the first snap ring expands into the first snap ring recess to allowentry of the first bone screw 42. Once the first bone screw 42 passesthe first snap ring, the first snap ring contracts, effectively blockingthe first bone screw 42 from backing out. The second opening 40similarly defines a second longitudinal axis 45, and is configured toreceive a second bone screw 46, and further includes a second snap ringrecess, which is configured to receive a second snap ring. The secondsnap ring effectively blocks the second bone screw 46 from backing outin a similar fashion to the first snap ring. The first longitudinal axis41 and the second longitudinal axis 45 diverge in a direction toward thedistal end 23 of the expandable disc replacement body 12.

The second wall 20 of the expandable disc replacement body 12 includes asecond space 49 for receiving bone graft, and a second bone-screwreceiving section 50 located on a proximal end 51 of the second wall 20.The second bone-screw receiving section 50 may angled back 3-5 degreesfrom vertical to decrease the profile. The second bone-screw receivingsection 50 includes a third flange 52, a fourth flange 53, a secondrecessed edge 54 located between the third flange 52 and the fourthflange 53 on an inferior edge 55 of the second bone-screw receivingsection 50, and a second grasping recess 56 located between the thirdflange 52 and the fourth flange 53 on a superior edge 57 of the secondbone-screw receiving section 50. The third flange 52 includes a thirdopening recess 58, which surrounds a third opening 59. The fourth flange53 includes a fourth opening recess 60, which surrounds a fourth opening61. The third opening 59 defines a third longitudinal axis 62, and isconfigured to receive a third bone screw 64, and further includes athird snap ring recess, which is configured to receive a third snapring. The fourth opening 61 defines a fourth longitudinal axis 70, andis configured to receive a fourth bone screw 72, and further includes afourth snap ring recess, which is configured to receive a fourth snapring. The third and fourth snap rings effectively block the third andfourth bone screws 64, 72 from backing out in a similar fashion to thefirst and second snap rings. The third longitudinal axis 62 and thefourth longitudinal axis 70 also diverge in a direction toward thedistal end 23 of the expandable disc replacement body 12. The firstthrough fourth snap rings and snap ring recesses described above areidentical to a snap ring 77 and a snap ring recess 78 illustrated inFIGS. 5 and 6.

The anterior cover plate 16 can be placed between the first and secondwalls 18, 20, and may further include grasping notches (not shown) whichsnap into the first and second grasping recesses 35, 56 of theexpandable disc replacement body 12. The anterior cover plate 16 furtherincludes a central defect 79, which can be used to inject bone graftinto the interior portion of the expandable disc replacement body 12.

The adjustment mechanism 14 comprises a first wedge 80 and a secondwedge 82. The first wedge 80 slidably engages the first wall 18 and thesecond wall 20 at one of the two lateral sides 24 of the expandable discreplacement body 12, and further includes a first wedge screw aperture83 configured to receive a first wedge translating screw 84. The firstwedge screw aperture 83 further includes a first wedge snap ring recessconfigured to receive a first wedge snap ring. The first wedgetranslating screw 84 threadably engages a first internally threadedcylinder 87, which is directly coupled to the hinge 21. The firstinternally threaded cylinder 87 may include an internal end wall toblock further penetration of the screw 84 beyond a position thatprovides an upper value of the angle (e.g., 12 degrees) between thefirst wall 18 and the second wall 20.

The second wedge 82 slidably engages the first wall 18 and the secondwall 20 at the other of the two lateral sides 24 of the expandable discreplacement body 12, and further includes a second wedge screw aperture88 configured to receive a second wedge translating screw 89, similar tothe first wedge 80. The second wedge screw aperture 88 further includesa second wedge snap ring recess configured to receive a second wedgesnap ring. The second wedge translating screw 89 threadably engages asecond internally threaded cylinder, similar to the first internallythreaded cylinder 87, which is also directly coupled to the hinge 21.

The first and second wedge snap rings and the first and second wedgesnap ring recesses described above are identical to the snap ring 77 andsnap ring recess 78, shown in FIGS. 5 and 6. The first and second wedgesnap rings also effectively block the first and second wedge translatingscrews from backing out in a similar fashion to the first through fourthsnap rings described above.

The spinal fixation system 10 further includes a disc replacement holder93. The disc replacement holder 93 includes handle 94, a connector shaft95, and an interface block 96. The disc replacement holder 93 furtherincludes a hollow passageway 97 passing through the handle 94, theconnector shaft 95 and the interface block 96, and housing a graspingmechanism 98. The grasping mechanism 98 is configured to grasp thegrasping recesses 35, 56 of the first and second bone-screw receivingsections 28, 50 when the grasping mechanism 98 is pushed out of an endof the hollow passageway 97 of the interface block 96. The interfaceblock 96 further includes four angled drill guide holes 99, which mayhave an inside diameter only slightly larger than the diameter of thebone screw heads.

Now that the structure of the first embodiment of the spinal fixationsystem 10 has been described, the functionality of the spinal fixationsystem 10 will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient.Then, the expandable disc replacement body 12 of the spinal fixationsystem 10 described above may be placed between the two adjacentvertebrae, such that the first bone-screw receiving section 28 isadjacent the superior of the two vertebrae and the second bone-screwreceiving section 50 is adjacent the inferior of the two vertebrae,which may be done using the disc replacement holder 93. Then, using thefour angled drill guide holes 99 on the interface block 96 of the discreplacement holder 93, pilot holes may be drilled into the superior andinferior vertebrae to aid in the insertion of the first through fourthbone screws 42, 46, 64, 72 into the vertebrae. A sounding rod may beinserted thorough the drill guide holes 99 into the pilot holes.

Once the expandable disc replacement body 12 is placed between the twoadjacent vertebrae, the first and second bone screws 42, 46 may bescrewed into the superior vertebra through the first and second openings38, 40, respectively, and the third and fourth bone screws 64, 72 may bescrewed into the inferior vertebra 73 through the third and fourthopenings 59, 61, respectively.

After the first through fourth bone screws 42, 46, 64, 72 are in place,the expandable disc replacement body 12 is effectively locked betweenthe two adjacent vertebrae. At this point, the adjustment mechanism 14can be used to achieve various angles between the first wall 18 and thesecond wall 20 of the expandable disc replacement body 12.

As first and second wedge translating screws 84, 89 are rotatedclockwise, they force the first and second wedges 80, 82 towards thedistal end 23 of the expandable disc replacement body 12, which due tothe shape and configuration of the first and second wedges 80, 82 withinthe first and second walls 18, 20, forces the first and second walls 18,20 to separate. Because the first and second walls 18, 20 are coupled atthe hinge 21, this separation increases an angle formed therebetween. Assuch, when the first and second wedge translating screws 84, 89 arerotated, the rotation can correlate to a predetermined change in theangle between the first and second walls 18, 20. This capability tochange the angle between the first and second walls 18, 20 allows forthe expandable disc replacement body 12 to be used to counteract variousdegrees of lordosis of the spine. The first and second wedge translatingscrews 84, 89 can include markings on the screw head wherein rotation ofthe screw head from one marking to the adjacent marking correlates witha predetermined change in the angle between the first and second walls18, 20. In another non-limiting example embodiment, one degree ofopening between the first and second walls 18, 20 can be provided perturn of the screw head.

The first wedge 80 and the second wedge 82 can also be inserted unequalamounts to create a first adjustment angle between the first and secondwalls 18, 20 on one lateral side 24 of the expandable disc replacementbody 12, and a different second adjustment angle between the first andsecond walls 18, 20 on the other lateral side 24 of the expandable discreplacement body 12. The difference between the first and secondadjustment angles may create a slight lateral angle between the firstand second walls 18, 20, which may further be used to counteractscoliosis of the spine. In this case, the hinge 21 may alternatively beformed of a pliable material coupling the first and second walls 18, 20to allow for biaxial rotation.

Referring now to FIGS. 7-9 and 12-13B, there is shown a secondembodiment of a spinal fixation system 210 according to the inventionimplanted on a spine. The spinal fixation system 210 includes a discreplacement body 212 and a plate 216. The disc replacement body 212includes a first wall 218 and a second wall 220. In some embodiments,the first wall 218 and the second wall 220 can be substantiallyparallel. In some other embodiments, the first wall 218 and the secondwall 220 can be angled such that a first distance between the first wall218 and the second wall 220 at a proximal end 222 of the discreplacement body 212 is larger than a second distance between the firstwall 218 and the second wall 220 at a distal end 223 of the discreplacement body 212. The first wall 218 and the second wall 220 furtherinclude a bone graft chamber 226 formed therebetween and capable ofreceiving bone graft.

The plate 216 includes a pair of opposed flanges 227, a first bone-screwreceiving section 228 at a superior edge 229 of the plate 216, and asecond bone-screw receiving section 230 at an inferior edge 231 of theplate 216. When the spinal fixation system 210 is assembled, the plate216 and the disc replacement body 212 are coupled together and the pairof opposed flanges 227 engage the first and second walls 218, 220 of thedisc replacement body 212, effectively limiting rotational motion of thedisc replacement body 212. The first bone-screw receiving section 228includes a first flange 233, a second flange 234, and a first recessededge 235 located between the first flange 233 and the second flange 234on the superior edge 229 of the plate 216. The first flange 233 and thesecond flange 234 include a first opening 238 and a second opening 240,respectively. The first opening 238 defines a first longitudinal axis241, is configured to receive a first bone screw 242, and may furtherinclude a first snap ring recess, which is configured to receive a firstsnap ring, as shown in FIGS. 5 and 6. In this case, when the first bonescrew 242 is received within the first opening 238, the first snap ringexpands into the first snap ring recess to allow entry of the first bonescrew 242. Once the first bone screw 242 passes the first snap ring, thefirst snap ring contracts, effectively blocking the first bone screw 242from backing out. The second opening 240 similarly defines a secondlongitudinal axis 245, is configured to receive a second bone screw 246,and may further include a second snap ring recess, which is configuredto receive a second snap ring, as shown in FIGS. 5 and 6. Again, in thiscase, the second snap ring effectively blocks the second bone screw 246from backing out in a similar fashion to the first snap ring. The firstlongitudinal axis 241 and the second longitudinal axis 245 diverge in adirection toward the distal end 223 of the disc replacement body 212.

The second bone-screw receiving section 230 includes a third flange 252,a fourth flange 253, and a second recessed edge 254 located between thethird flange 252 and the fourth flange 253 on the inferior edge 231 ofthe plate 216. The third flange 252 and the fourth flange 253 include athird opening 259 and a fourth opening 261, respectively. The thirdopening 259 defines a third longitudinal axis 262, is configured toreceive a third bone screw 264, and may further includes a third snapring recess, which is configured to receive a third snap ring, as shownin FIGS. 5 and 6. The fourth opening 261 defines a fourth longitudinalaxis 270, is configured to receive a fourth bone screw 272, and mayfurther include a fourth snap ring recess, which is configured toreceive a fourth snap ring, as shown in FIGS. 5 and 6. The third andfourth snap rings effectively block the third and fourth bone screws264, 272 from backing out in a similar fashion to the first and secondsnap rings. The third longitudinal axis 262 and the fourth longitudinalaxis 270 also diverge in a direction toward the distal end 223 of thedisc replacement body 212.

The disc replacement body 212 and the plate 216 of the spinal fixationsystem 210 can be coupled in a multitude of methods. In someembodiments, the disc replacement body 212 can be coupled to the plate216 using a screw 284 located centrally on the plate 216 such that theplate 216 is coupled to the proximal end 222 of the disc replacementbody 212. In some other embodiments, the pair of opposed flanges 227 canbe a pair of opposed moveable flanges 286, such that they can movetowards each other and apart from one another, as shown in FIGS. 13A and13B. In this case, the pair of opposed moveable flanges 286 can movetogether to grasp the disc replacement body 212 such that the plate 216is coupled to the proximal end 222 of the disc replacement body 212.

As shown in FIGS. 13A and 13B, the pair of opposed moveable flanges 286can be moveable using a rack and pinion adjustment mechanism 288. Usingthe rack and pinion adjustment mechanism 288, a central gear 290 can berotated to force a pair of gear toothed bars 292, which are coupled tothe pair of opposed moveable flanges 286, to move relative to eachother. As the pair of gear toothed bars 292 move relative to each other,the pair of opposed moveable flanges 286 can move towards each other orapart from each other. Once the pair of opposed moveable flanges 286 arein a desired position, they can be locked in place using a set screw294.

Now that the structure of the second embodiment of the spinal fixationsystem 210 has been described, the functionality of the spinal fixationsystem 210 will be described below.

According to one method of use, the spinal fixation system 210 isassembled prior to surgery, such that the plate 216 is coupled to theproximal end 222 of the disc replacement body 212. Then, during surgery,a surgeon first removes an intervertebral disc from between two adjacentvertebrae of a patient. Then, the disc replacement body 212 of thespinal fixation system 210 described above may be placed between the twoadjacent vertebrae, such that the first bone-screw receiving section 228of the plate 216 is adjacent the superior of the two vertebrae and thesecond bone-screw receiving section 230 is adjacent the inferior of thetwo vertebrae.

Once the disc replacement body 212 is placed between the two adjacentvertebra, the first and second bone screws 242, 246 may be screwed intothe superior vertebra through the first and second openings 238, 240,respectively, and the third and fourth bone screws 264, 272 may bescrewed into the inferior vertebra through the third and fourth openings259, 261, respectively.

After the first through fourth bone screws, 242, 246, 264, 272 are inplace, the disc replacement body 212 is effectively locked between thetwo adjacent vertebrae.

Alternatively, the plate 216 can be coupled to the proximal end 222 ofthe disc replacement body 212 after the disc replacement body 212 isplaced between the two adjacent vertebrae.

Turning now to FIGS. 10A-11, there is shown a third embodiment of aspinal fixation system 310 according to the invention implanted on aspine. The spinal fixation system 310 includes a disc replacement bodyportion 312 and a plate portion 316. The disc replacement body portion312 and the plate portion 316 are a unitary component and are comprisedof a material continuously forming the disc replacement body portion 312and the plate portion 316. Said differently, the disc replacement bodyportion 312 and the plate portion 316 are a unitary component, such thatthe entire unitary component may be molded, cast, or otherwise formed ina single piece, with no assembly required. The disc replacement bodyportion 312 includes a first wall 318 and a second wall 320. In someembodiments, the first wall 318 and the second wall 320 can besubstantially parallel. In some other embodiments, the first wall 318and the second wall 320 can be angled such that a first distance betweenthe first wall 318 and the second wall 320 at a proximal end 322 of thedisc replacement body portion 312 is larger than a second distancebetween the first wall 318 and the second wall 320 at a distal end 323of the disc replacement body portion 312. The first wall 318 and thesecond wall 320 further include a bone graft chamber 326 formedtherebetween and capable of receiving bone graft.

The plate portion 316 includes a first bone-screw receiving section 328at a superior edge 329 of the plate portion 316, and a second bone-screwreceiving section 330 at an inferior edge 331 of the plate portion 316.The first bone-screw receiving section 328 includes a first flange 333,a second flange 334, and a first recessed edge 335 located between thefirst flange 333 and the second flange 334 on the superior edge 329 ofthe plate portion 316. The first flange 333 and the second flange 334include a first opening 338 and a second opening 340, respectively. Thefirst opening 338 defines a first longitudinal axis 341, is configuredto receive a first bone screw 342, and may further include a first snapring recess, which is configured to receive a first snap ring, as shownin FIGS. 5 and 6. When the first bone screw 342 is received within thefirst opening 338, the first snap ring expands into the first snap ringrecess to allow entry of the first bone screw 342. Once the first bonescrew 342 passes the first snap ring, the first snap ring contracts,effectively blocking the first bone screw 342 from backing out. Thesecond opening 340 similarly defines a second longitudinal axis 345, isconfigured to receive a second bone screw 346, and may further include asecond snap ring recess, which is configured to receive a second snapring, as shown in FIGS. 5 and 6. The second snap ring effectively blocksthe second bone screw 346 from backing out in a similar fashion to thefirst snap ring. The first longitudinal axis 341 and the secondlongitudinal axis 345 diverge in a direction toward the distal end 323of the disc replacement body portion 312.

The second bone-screw receiving section 330 includes a third flange 352,a fourth flange 353, and a second recessed edge 354 located between thethird flange 352 and the fourth flange 353 on the inferior edge 331 ofthe plate portion 316. The third flange 352 and the fourth flange 353include a third opening 359 and a fourth opening 361, respectively. Thethird opening 359 defines a third longitudinal axis 362, is configuredto receive a third bone screw 364, and may further include a third snapring recess, which is configured to receive a third snap ring, as shownin FIGS. 5 and 6. The fourth opening 361 defines a fourth longitudinalaxis 370, is configured to receive a fourth bone screw 372, and mayfurther include a fourth snap ring recess, which is configured toreceive a fourth snap ring, as shown in FIGS. 5 and 6. The third andfourth snap rings effectively block the third and fourth bone screws364, 372 from backing out in a similar fashion to the first and secondsnap rings. The third longitudinal axis 362 and the fourth longitudinalaxis 370 also diverge in a direction toward the distal end 323 of thedisc replacement body portion 312.

Having described the structure of the third embodiment of the spinalfixation system 310, the functionality of the spinal fixation system 310will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient.Then, the disc replacement body portion 312 of the spinal fixationsystem 310 described above may be placed between the two adjacentvertebrae, such that the first bone-screw receiving section 328 isadjacent the superior of the two vertebrae and the second bone-screwreceiving section 330 is adjacent the inferior of the two vertebrae.

Once the disc replacement body portion 312 is placed between the twoadjacent vertebrae, the first and second bone screws 342, 346 may bescrewed into the superior vertebra through the first and second openings338, 340, respectively, and the third and fourth bone screws 364, 372may be screwed into the inferior vertebra through the third and fourthopenings 359, 361, respectively.

After the first through fourth bone screws, 342, 346, 364, 372 are inplace, the disc replacement body portion 312 is effectively lockedbetween the two adjacent vertebrae.

Referring now to FIG. 14, there is shown a multi-level spinal fixationsystem 410 according to the invention implanted on a spine. Themulti-level spinal fixation system 410 includes a first spinal fixationsystem 412, a second spinal fixation system 414, a third spinal fixationsystem 416, and a clamp 418 dimensioned to couple together the first,second, and third spinal fixation systems 412, 414, 416 when the first,second, and third spinal fixation systems 412, 414, 416 are implanted indifferent intervertebral disc spaces. Each of the first, second, andthird spinal fixation systems 412, 414, 416 can be any of the previouslydescribed embodiments (corresponding to spinal fixation system 10,spinal fixation system 210, or spinal fixation system 310) or can be anyother spinal fixation systems that may be used during spinal discreplacement surgery. Each of the first, second and third spinal fixationsystems 412, 414, 416 further include a fixing element 420. The clamp418 includes an elliptical perimeter 422 and an elongated slot 424,configured to receive the fixing elements 420 of the first, second, andthird spinal fixation systems 412, 414, 416. The clamp 418 may have abackout flange.

According to one method of use, in surgery, a surgeon would first removethe intervertebral discs from between multiple pairs of adjacentvertebrae of a patient. Then, any of the disc replacement bodies or bodyportions 12, 212, 312 of any of the spinal fixation systems 10, 210, 310described above may be placed between the multiple pairs of adjacentvertebrae, effectively replacing the intervertebral discs. Once thespinal fixation systems 10, 210, 310 are between the multiple pairs ofadjacent vertebrae of the patient, they are screwed into the multiplepairs of adjacent vertebrae, using bone screws, as described above.

After the bone screws are in place, the spinal fixation systems 10, 210,310 are effectively locked between the multiple pairs of adjacentvertebrae. The fixing elements 420 can then be coupled together by theclamp 418. At this point the fixing elements 420 are received within theelongated slot 424 of the clamp 418, such that they are spatially fixedrelative to each other.

Turning now to FIG. 15, there is shown a kit 510 for determining anappropriate sized disc replacement body for spinal surgery according tothe invention. The kit 510 comprises a plurality of disc replacementtrial components 512 and a detachable handle 514 configured to removablyengage any of the plurality of disc replacement trial components 512.

Each of the plurality of disc replacement trial components 512 havedifferent exterior dimensions and comprise a body 516 and a platesection 518. Each body 516 further includes a first wall 520 and asecond wall 522. Each plate section 518 further includes a firstbone-screw drill guide section 524 at a superior end 526 of the platesection 518 and a second bone-screw drill guide section 528 at aninferior end 530 of the plate section 518. The first bone-screw drillguide section 524 includes two first bone-screw drill guide sectionholes 532. Similarly, the second bone-screw drill guide section 528includes two second bone-screw drill guide section holes 536.

The plurality of disc replacement trial components 512 further includesa first disc replacement trial component 540, a second disc replacementtrial component 542, and a third disc replacement trial component 544.Although in the illustrated embodiment, there are three disc replacementtrial components 512, in other embodiments there can be two or more discreplacement trial components 512.

In some instances, an angle between the first wall 520 and the secondwall 522 of the body 516 of the first disc replacement trial component540 can be different than a second angle between the first wall 520 andthe second wall 522 of the body 516 of the second disc replacement trialcomponent 542. In other instances, the first and second angles can bethe same. The width of the trials can be short enough that the surgeoncan confirm safe depth of the graft.

According to one method of use, in surgery, a surgeon first removes theintervertebral disc from between a pair of adjacent vertebrae of apatient. Then, the surgeon uses the plurality of disc replacement trialcomponents 512 of the kit 510 to determine the necessary size of a discreplacement body to be inserted into the intervertebral space byindividually and consecutively placing the plurality of disc replacementtrial components 512 between the pair of adjacent vertebrae, until oneof the plurality of disc replacement trial components 512 is deemed thecorrect size.

Once a trial is deemed the correct size, the surgeon can then drillpilot holes into the pair of adjacent vertebrae using the first throughfourth bone-screw drill guide holes 532, 534, 536, 538. These pilotholes can then be used for the insertion of bone screws, which can beused to lock a spinal fixation system in place between the pair ofadjacent vertebrae, as described with respect to the other embodimentsof the invention above.

Referring now to FIG. 16, there is shown a fourth embodiment of a spinalfixation system 610 according to the invention implanted on a spine. Thespinal fixation system 610 includes an expandable disc replacement body612, and an adjustment mechanism 614. The expandable disc replacementbody 612 includes a first wall 618, a second wall 620, and a hinge 621including a pin 622 attaching the first wall 618 and the second wall 620at a posterior end 623 of the expandable disc replacement body 612.

The disc replacement body 612 may comprise a metallic material, such astitanium, cobalt chrome or stainless steel, or a polymeric material,such as polyetheretherketone.

The first wall 618 further includes a first bone anchor 632 on asuperior surface 634 of the first wall 618. The first bone anchor 632 isconfigured to provide stabilization to the spinal fixation system 610when the spinal fixation system 610 is implanted between two adjacentvertebrae, as also described below. Similarly, the second wall 620further includes a second bone anchor 636 on an inferior surface 638 ofthe second wall 620. Again, the second bone anchor 636 is alsoconfigured to provide stabilization to the spinal fixation system 610when the spinal fixation system 610 is implanted between two adjacentvertebrae, as also described below.

The adjustment mechanism 614 comprises a jack mechanism 679 including aleadscrew 681, two upper legs 685, and two lower legs 686. The leadscrew681 further includes a head 690 on a posterior end of the leadscrew 681.The head 690 is configured to be posteriorly accessed and rotated by ascrewdriver 691. The screwdriver 691 may be torque limited, to preventexcessive force that could fracture the adjacent vertebrae.Additionally, the two upper legs 685 are hingedly coupled to the firstwall 618 at superior ends of the two upper legs 685 and are threadablycoupled to the leadscrew 681 at inferior ends of the two upper legs 685.Similarly, the two lower legs 686 are hingedly coupled to the secondwall 620 at inferior ends of the two lower legs 686 and are threadablycoupled to the leadscrew 681 at superior ends of the two lower legs 686.

Now that the structure of the fourth embodiment of the spinal fixationsystem 610 has been described, the functionality of the spinal fixationsystem 610 will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient.Then, the expandable disc replacement body 612 of the spinal fixationsystem 610 described above may be placed between the two adjacentvertebrae, such that the first wall 618 is adjacent the superior of thetwo vertebrae and the second wall 620 is adjacent the inferior of thetwo vertebrae. Then, once the expandable disc replacement body 612 isplaced between the two adjacent vertebrae, the adjustment mechanism 614can be used to achieve various angles between the first wall 618 and thesecond wall 620 of the expandable disc replacement body 612. The anglesdescribed herein are formed between the first wall 618 and the secondwall 620, with the hinge 621 nominally forming the vertex of the angle.

As the leadscrew 681 is posteriorly rotated clockwise, the leadscrew 681threadably engages the two upper legs 685, bringing the inferior ends ofthe two upper legs 685 towards each other. The leadscrew 681 similarlyengages the two lower legs 686, bringing the superior ends of the twolower legs 686 towards each other. As the inferior ends of the two upperlegs 685 and the superior ends of the two lower legs 686 are pulledtowards each other by the leadscrew 681, the superior ends of the twoupper legs 685 are forced away from the inferior ends of the two lowerlegs 686. This results in the first wall 618 being forced away from thesecond wall 620, thereby increasing an angle formed therebetween. Whenthe expandable disc replacement body 612 is implanted between the twoadjacent vertebrae, the angle between the first wall 618 and the secondwall 620 is negative (i.e., the anterior ends of the first and secondwalls 618, 620 are closer than the posterior ends of the first andsecond walls 618, 620). As the leadscrew 681 is rotated, angle betweenthe first wall 618 and the second wall 620 becomes less negative, andeventually, the first wall 618 becomes parallel with the second wall620. When the first wall 618 is parallel with the second wall 620, theexpandable disc replacement body 612 is considered to be in a neutralposition. In some embodiments, as the leadscrew 681 is rotated, thespinal fixation system 610 can be configured to give a tactile feedbackinforming the surgeon when the expandable disc replacement body 612 hasreached the neutral position. Further, as the first wall 618 and thesecond wall 620 are forced apart, the superior surface 634 of the firstwall 618, and the inferior surface 638 of the second wall 620 contactthe two adjacent vertebrae. As the superior surface 634 and inferiorsurface 638 come into contact with the two adjacent vertebrae, the firstand second bone anchors 632, 636 slightly pierce the vertebrae, therebyproviding stabilization to the spinal fixation system 610.

Additionally, when the leadscrew 681 is rotated, the rotation cancorrelate to a predetermined change in the angle between the first andsecond walls 618, 620. This capability to change the angle between thefirst and second walls 618, 620 allows for the expandable discreplacement body 612 to be used to counteract various degrees oflordosis of the spine. The leadscrew 681 can include markings on thehead 690 wherein rotation of the head 690 from one marking to theadjacent marking correlates with a predetermined change in the anglebetween the first and second walls 618, 620.

In some embodiments, there may be a first jack mechanism and a secondmechanism disposed on opposite lateral sides of the expandable discreplacement body 612. In these cases, the first and second jackmechanisms can be adjusted individually, thereby creating a firstadjustment angle on a first lateral side that is different than a secondadjustment angle on a second lateral side. The difference between thefirst and second adjustment angles may create a slight lateral anglebetween the first and second walls 618, 620, which may further be usedto counteract scoliosis of the spine. In this case, the hinge 621 mayalternatively be formed of a pliable material coupling the first andsecond walls 618, 620 to allow for biaxial rotation.

Referring now to FIG. 17, there is shown a fifth embodiment of a spinalfixation system 710 according to the invention implanted on a spine. Thespinal fixation system 710 is substantially similar to the spinalfixation system 10 described above, with like parts labeled with likenumbers (e.g., first wall 18 and first wall 718, hinge 21 and hinge 721,etc.). The adjustment mechanism 714 of the spinal fixation system 710,however, comprises a jack mechanism 779. The jack mechanism 779 includesa leadscrew 781, two upper legs 785, and two lower legs 786. Theleadscrew 781 further includes a head 790 on an anterior end of theleadscrew 781. The head 790 is configured to anteriorly accessed androtated by a screwdriver (not shown). Additionally, the two upper legs785 are hingedly coupled to the first wall 718 at superior ends of thetwo upper legs 785 and are threadably coupled to the leadscrew 781 atinferior ends of the two upper legs 785. Similarly, the two lower legs786 are hingedly coupled to the second wall 720 at inferior ends of thetwo lower legs 786 and are threadably coupled to the leadscrew 781 atsuperior ends of the two lower legs 786.

Now that the structure of the fifth embodiment of the spinal fixationsystem 710 has been described, the functionality of the spinal fixationsystem 710 will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient.Then, the expandable disc replacement body 712 of the spinal fixationsystem 710 described above may be placed between the two adjacentvertebrae, such that the first wall 718 is adjacent the superior of thetwo vertebrae and the second wall 720 is adjacent the inferior of thetwo vertebrae. Then, once the expandable disc replacement body 712 isplaced between the two adjacent vertebrae, the adjustment mechanism 714can be used to achieve various angles the first wall 718 and the secondwall 720 of the expandable disc replacement body 712.

As the leadscrew 781 is anteriorly rotated clockwise, the leadscrew 781threadably engages the two upper legs 785, bringing the inferior ends ofthe two upper legs 785 towards each other. The leadscrew 781 similarlyengages the two lower legs 786, bringing the superior ends of the twolower legs 786 towards each other. As the inferior ends of the two upperlegs 785 and the superior ends of the two lower legs 786 are pulledtowards each other by the leadscrew 781, the superior ends of the twoupper legs 785 are forced away from the inferior ends of the two lowerlegs 786. This results in the first wall 718 being forced away from thesecond wall 720, thereby increasing an angle formed therebetween. Assuch, when the leadscrew 781 is rotated, the rotation can correlate to apredetermined change in the angle between the first and second walls718, 720. This capability to change the angle between the first andsecond walls 718, 720 allows for the expandable disc replacement body712 to be used to counteract various degrees of lordosis of the spine.The leadscrew 781 can include markings on the head 790 wherein rotationof the head 790 from one marking to the adjacent marking correlates witha predetermined change in the angle between the first and second walls718, 720.

In some embodiments, there may be a first jack mechanism and a secondmechanism disposed on opposite lateral sides of the expandable discreplacement body 712. In these cases, the first and second jackmechanisms can be adjusted individually, thereby creating a firstadjustment angle on a first lateral side that is different than a secondadjustment angle on a second lateral side. The difference between thefirst and second adjustment angles may create a slight lateral anglebetween the first and second walls 718, 720, which may further be usedto counteract scoliosis of the spine. In this case, the hinge 721 mayalternatively be formed of a pliable material coupling the first andsecond walls 718, 720 to allow for biaxial rotation.

Turning now to FIGS. 18 and 19, there is shown a sixth embodiment of aspinal fixation system 810 according to the invention implanted on aspine. The spinal fixation system 810 includes a disc replacement body812. The disc replacement body 812 includes a first wall 818 and asecond wall (not shown) opposite the first wall 818. In someembodiments, the first wall 818 and the second wall can be substantiallyparallel. In some other embodiments, the first wall 818 and the secondwall can be angled such that a first distance between the first wall 818and the second wall at a proximal end 822 of the disc replacement body812 is larger than a second distance between the first wall 818 and thesecond wall at a distal end 823 of the disc replacement body 812. Thefirst wall 818 and the second wall further include a bone graft chamber826 formed therebetween and capable of receiving bone graft.

The spinal fixation system 810 further includes a pair of wings 879disposed on a superior surface of the spinal fixation system 810. Thepair of wings 879 are deployable from a retracted position (as shown inFIG. 18) to an extended position (as shown in FIG. 19). The spinalfixation system 810 also includes a pair of locking pins 881 on theproximal end 822 of the disc replacement body 812 configured to engagethe pair of wings 879, thereby locking them in place.

Having described the structure of the sixth embodiment of the spinalfixation system 810, the functionality of the spinal fixation system 810will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient,with the pair of wings 879 in the retracted position. Then, the discreplacement body portion 812 of the spinal fixation system 810 describedabove may be placed between the two adjacent vertebrae, such that thefirst wall 818 is adjacent a superior of the two vertebrae and the lowerwall is adjacent an inferior of the two vertebrae.

Once the disc replacement body 812 is placed between the two adjacentvertebrae, the surgeon can deploy the pair of wings 879 from theretracted position to the extended position. With the pair of wings 879in the extended position, the contact surface (i.e., the amount ofsurface area of the disc replacement body 812 making contact with theadjacent vertebrae) is greatly increased. This increase in contactsurface can reduce the local stress (i.e., point pressure) experiencedby the adjacent vertebrae, and thereby lower subsidence risk. Theincrease in contact surface can also increase friction between the discreplacement body 812 and the adjacent vertebrae, aiding in stabilizingthe spinal fixation system 810 while the spinal fixation system 810 isimplanted in the spine, aiding in the prevention of backout into thespinal canal and resultant neurological compression.

Once the pair of wings 879 are deployed, the locking pins 881 can beused to lock the pair of wings 879 in place, acting as rigidly fixedlateral extensions.

Referring now to FIGS. 20 and 21, there is shown a seventh embodiment ofa spinal fixation system 910 according to the invention implanted on aspine. The spinal fixation system 910 includes a disc replacement body912 and a plurality of adjustment mechanisms 914. The disc replacementbody 912 includes a first wall 918, a second wall 920, and a joint 921connecting the first wall 918 and the second wall 920. The joint 921further includes a socket portion 922, a ball portion 923 received inthe socket portion 922, and a pin 924 configured to lock the joint 921,thereby preventing relative movement between the first wall 918 and thesecond wall 920. The disc replacement body 912 may comprise a metallicmaterial, such as titanium, cobalt chrome, or stainless steel, or apolymeric material, such as polyetheretherketone. The first wall 918 andthe second wall 920 may further be perforated. This perforation mayprovide channels for bone graft, such as allograft bone to grow throughthe first and second walls 918, 920. This bone-ingrowth allows forbiological fixation of the spinal fixation system 910. Furthermore, thefirst wall 918 and the second wall 920 may have a slight concavity tobetter match the contours of the two adjacent vertebrae, therebyallowing for more symmetric pressure distribution.

The plurality of adjustment mechanisms 914 includes four jack mechanisms979 similar to the jack mechanism 679. Each of the jack mechanisms 979similarly include a leadscrew 981, two upper legs 985, and two lowerlegs 986. Each leadscrew 981 further includes a head (not shown) that isconfigured to be accessed and rotated by a screwdriver (not shown).Additionally, the two upper legs 985 are hingedly coupled to the firstwall 918 at superior ends of the two upper legs 985. Similarly, the twolower legs 986 are hingedly coupled to the second wall 920 at inferiorends of the two lower legs 986 and are threadably coupled to theleadscrew 981 at superior ends of the two lower legs 986.

Each of the plurality of adjustment mechanisms 914 further include alocking mechanism 990 including a rod 991, a cylinder 992, a spring 993,and a locking pin 994. The rod 991 is rigidly fixed to the first wall918 and is partially enveloped by the cylinder 992. The cylinder 992 isrigidly fixed to the second wall 920. The spring 993 is disposed withinthe cylinder 992 between the second wall 920 and the rod 991. The spring993 biases the rod 991 away from the second wall 920. The plurality ofadjustment mechanisms 914 are disposed at corners of the discreplacement body 912. As such, the springs 993 of each of the pluralityof adjustment mechanisms 914 bias the first wall 918 and the second wall920 into a generally parallel configuration. The locking pin 994 isconfigured to lock the rod 991 relative to the cylinder 992, therebyrigidly fixing the locking mechanism 990.

Now that the structure of the seventh embodiment of the spinal fixationsystem 910 has been described, the functionality of the spinal fixationsystem 910 will be described below.

According to one method of use, in surgery, a surgeon first removes anintervertebral disc from between two adjacent vertebrae of a patient.Then, the disc replacement body 912 of the spinal fixation system 910described above may be placed between the two adjacent vertebrae, suchthat the first wall 918 is adjacent the superior of the two vertebrae,such that the first wall 918 is adjacent the superior of the twovertebrae and the second wall 920 is adjacent the inferior of the twovertebrae. Then, once the disc replacement body 912 is place between thetwo adjacent vertebrae, the plurality of adjustment mechanisms 914 canbe used to achieve various angles between the first wall 918 and thesecond wall 920 of the disc replacement body 912. The plurality ofadjustment mechanisms 914, disposed at the corners of the discreplacement body 912, may further provide multi-planar spinalcorrection.

An advantage of this embodiment, is that multi-planar correction throughthe disc space, which is the natural mobile separation between elementsof the spinal column, eliminates or reduces the need for osteotomieswhich create false separations to allow for similar multi-planarcorrections. A further advantage is that this technique allows forimproved precision. Traditional osteotomies result in angular correctionbased on the angle and magnitude of osteotomy cuts. This is far lessprecise that the method taught here.

As the leadscrews 981 of each of the plurality of jack mechanisms 979are rotated, the first wall 918 and the second wall 920 can be forcedapart at a corresponding corner of the disc replacement body 912. As thefirst wall 918 and the second wall 920 at one corner are forced apart,the first wall 918 and the second wall 920 rotate about the joint 921,resulting in the first wall 918 and the second wall 920 being forcedtogether at an opposing corner.

Once the surgeon adjusts the plurality of adjustment mechanism 914 toachieve a desired angle, the surgeon can use the pin 924 to lock thejoint 921 and can further additionally or alternatively use the lockingpins 994 rigidly fix the locking mechanisms 990, thereby locking thefirst wall 918 relative to the second wall 920.

Referring now to FIGS. 22 to 27, there is shown an eighth embodiment ofa spinal fixation system 1010 according to the invention. The spinalfixation system 1010 includes an expandable disc replacement body 1012,and an adjustment mechanism 1014. The expandable disc replacement body1012 includes a first wall 1018, a second wall 1020, a hinge 1021attaching the first wall 1018 and the second wall 1020 at a distal end1023 of the expandable disc replacement body 1012, and two lateral sides1024. The disc replacement body 1012 may comprise a metallic material,such as titanium, cobalt chrome or stainless steel, a polymericmaterial, such as polyetheretherketone, or a ceramic material.

The first wall 1018 of the expandable disc replacement body 1012includes a first space 1026 for receiving bone graft, such as allograftbone, and a first bone-screw receiving section 1028 located on aproximal end 1030 of the first wall 1018. The first bone-screw receivingsection 1028 includes a first flange 1032, and a first grasping recess1035 on an inferior edge 1036 of the first bone-screw receiving section1028. The first bone-screw receiving section 1028 is angled back fromvertical to decrease the profile. The first flange 1032 may terminate inan overhang to prevent bone graft from backing out of the first space1026. The first flange 1032 includes a first opening 1038 and a secondopening 1040. The first opening 1038 defines a first longitudinal axis1041, and is configured to receive a first bone screw. The secondopening 1040 similarly defines a second longitudinal axis 1045, and isconfigured to receive a second bone screw. The first longitudinal axis1041 and the second longitudinal axis 1045 diverge in a direction towardthe distal end 1023 of the expandable disc replacement body 1012. Firstand second snap rings and snap ring recesses, which are identical tosnap ring 77 and snap ring recess 78 illustrated in FIGS. 5 and 6, canbe used in the first opening 1038 and the second opening 1040 toeffectively block the first and second bone screws from backing out. Thefirst flange 1032 may include additional holes at medial and lateral endsections of the first flange 1032 so that sutures can be threadedthrough the holes and tied to hold the expandable disc replacement body1012 in place.

The second wall 1020 of the expandable disc replacement body 1012includes a second space 1049 for receiving bone graft, and a secondbone-screw receiving section 1050 located on a proximal end 1051 of thesecond wall 1020. The second bone-screw receiving section 1050 mayangled back from vertical to decrease the profile. The second bone-screwreceiving section 1050 includes a second flange 1052, and a secondgrasping recess 1056 located on a superior edge 1057 of the secondbone-screw receiving section 1050. The second flange 1052 may terminatein an overhang to prevent bone graft from backing out of the secondspace 1049. The second flange 1052 includes a third opening 1059 and afourth opening 1061. The third opening 1059 defines a third longitudinalaxis 1062, and is configured to receive a third bone screw. The fourthopening 1061 defines a fourth longitudinal axis 1070, and is configuredto receive a fourth bone screw 72. The third longitudinal axis 1062 andthe fourth longitudinal axis 1070 also diverge in a direction toward thedistal end 1023 of the expandable disc replacement body 1012. Third andfourth snap rings and snap ring recesses, which are identical to snapring 77 and snap ring recess 78 illustrated in FIGS. 5 and 6, can beused in the third opening 1059 and the fourth opening 1061 toeffectively block the third and fourth bone screws from backing out. Thesecond flange 1052 may include additional holes at medial and lateralend sections of the second flange 1052 so that sutures can be threadedthrough the holes and tied to hold the expandable disc replacement body1012 in place.

The hinge 1021 of the expandable disc replacement body 1012 is formedusing a first arcuate structure 1101 at the distal end of the first wall1018, an opposed second arcuate structure 1102 at the distal end of thefirst wall 1018, a first cylindrical structure 1091 at the distal end ofthe second wall 1020, and a second cylindrical structure 1092 at thedistal end of the second wall 1020. The first arcuate structure 1101surrounds the first cylindrical structure 1091 for rotation of the firstarcuate structure 1101 with respect to the first cylindrical structure1091, and the second arcuate structure 1102 surrounds the secondcylindrical structure 1092 for rotation of the second arcuate structure1102 with respect to the second cylindrical structure 1092. The hinge1021 comprises a bar 1025 connecting the first arcuate structure 1101and the second arcuate structure 1102. The bar 1025 is convex on a sidefacing the first space 1026 of the first wall 1018.

A first arcuate length of the first arcuate structure 1101 is used tolimit the angular rotation of the first arcuate structure 1101 about thefirst cylindrical structure 1091 in that a terminal end 1105 of thefirst arcuate structure 1101 contacts a stop wall 1106 that extends fromthe first cylindrical structure 1091. The angular location of theterminal end 1105 of the first arcuate structure 1101 is determined byvarying the first arcuate length of the first arcuate structure 1101.Likewise, a second arcuate length of the second arcuate structure 1102is used to limit the angular rotation of the second arcuate structure1102 about the second cylindrical structure 1092 in that a terminal end1115 of the second arcuate structure 1102 contacts a stop wall 1116 thatextends from the second cylindrical structure 1092. The angular locationof the terminal end 1115 of the second arcuate structure 1102 isdetermined by varying the second arcuate length of the second arcuatestructure 1102. In one non-limiting embodiment, the angular rotation ofthe first arcuate structure 1101 about the first cylindrical structure1091 and the angular rotation of the second arcuate structure 1102 aboutthe second cylindrical structure 1092 can be varied between a lowervalue of the angle of 0° and an upper value of the angle of 12°.

In order to easily assemble the spinal fixation system 1010, slots 1501,1502 can be arranged in the lateral sidewalls of the first flange 1032.The first flange 1032 can slide onto the second flange 1052.

The adjustment mechanism 1014 comprises a first wedge 1080. A lower tab1131 of the first wedge 1080 slidably engages the second wall 1020 in achannel 1132 of the second wall 1020. The first wedge 1080 includes afirst wedge screw aperture 1083 configured to receive a first wedgetranslating screw 1084. The first wedge translating screw 1084threadably engages a first internally threaded cylinder 1087, which is aportion of the first cylindrical structure 1091. A washer 1097 is at thedistal side of the first wedge 1080 to prevent the first wedge 1080 fromsliding out of place by moving distally on the screw 1084. Optionally, aguide post can also be located in the channel 1132 for extending into aguide hole of the first wedge 1080. The first wedge 1080 includes alateral protrusion 1135 that moves in a first guide channel 1136 of thefirst wall 1018, and engages an inner surface 1137 of the first guidechannel 1136. Optionally, the first wedge 1080 may further include alower lateral protrusion that moves in a guide channel of the secondwall 1020 similar to guide channel 1136 of the first wall 1018. Inanother option, the guide post located in the channel 1132 could bethreaded and used to guide a jam nut until it rests flush with the firstwedge 1080. The jam nut could also screw into receiving threads in thefirst wedge 1080. This mechanism would prevent the first wedgetranslating screw 1084, used in the first wedge 1080, from backingout/further penetrating the expandable disc replacement body 1012 due tomicro-motion and vibration. The jam nut would be threaded onto the postas a final step in the procedure, once the angle of the expandable discreplacement body 1012 has been set, the bone graft inserted, and theexpandable disc replacement body 1012 has been compressed to help securethe graft.

In another option, the guide post could function differently as a tine(no threads), and be bent superiorly to block the first wedgetranslating screw 1084 from backing out. Once the final position of theexpandable disc replacement body 1012 has been set, the tine could bebent upward, into the screw head's slot. The slot could be modified toinclude more than one final vertical position required to receive thetine. For example, an “X” shape pattern, or a “+” shape pattern, or a“*” shape pattern could be incorporated on the screw head, lending morefinal angle position options (rather than being confined to integerangle values at each full turn). Using this principle, if the tine isbent into the screw head's slot, the screw cannot turn, and thereforewill not back-out/protrude after its final position is set.

The adjustment mechanism 1014 comprises a second wedge 1082. A lower tab1143 of the second wedge 1082 slidably engages the second wall 1020 in achannel 1144 of the second wall 1020. The second wedge 1082 includes asecond wedge screw aperture 1088 configured to receive a second wedgetranslating screw 1089, similar to the first wedge 1080. The secondwedge translating screw 1089 threadably engages a second internallythreaded cylinder 1093, which is a portion of the second cylindricalstructure 1092. A washer 1099 is at the distal side of the second wedge1082 to prevent the second wedge 1082 from sliding out of place bymoving distally on the screw 1089. Optionally, a guide post can also belocated in the channel 1144 for extending into a guide hole of thesecond wedge 1082. The second wedge 1082 includes a lateral protrusion1145 that moves in a second guide channel 1146 of the first wall 1018,and engages an inner surface 1147 of the second guide channel 1146.Optionally, the second wedge 1082 may further include a lower lateralprotrusion that moves in a guide channel of the second wall 1020 similarto guide channel 1146 of the first wall 1018. In another option, theguide post could be threaded and used to guide a jam nut until it restsflush with the second wedge 1082 as described above with reference tothe first wedge 1080.

In another option, the guide post could function differently as a tine(no threads), and be bent superiorly to block the second wedgetranslating screw 1089 from backing out. Once the final position of theexpandable disc replacement body 1012 has been set, the tine could bebent upward, into the screw head's slot. The slot could be modified toinclude more than one final vertical position required to receive thetine. For example, an “X” shape pattern, or a “+” shape pattern, or a“*” shape pattern could be incorporated on the screw head, lending morefinal angle position options (rather than being confined to integerangle values at each full turn). Using this principle, if the tine isbent into the screw head's slot, the screw cannot turn, and thereforewill not back-out/protrude after its final position is set.

Now that the structure of the eighth embodiment of the spinal fixationsystem 1010 has been described, the functionality of the spinal fixationsystem 1010 will be described below. According to one method of use, insurgery, a surgeon first removes an intervertebral disc from between twoadjacent vertebrae of a patient. Then, the expandable disc replacementbody 1012 of the spinal fixation system 1010 described above may beplaced between the two adjacent vertebrae, such that the firstbone-screw receiving section 1028 is adjacent the superior of the twovertebrae and the second bone-screw receiving section 1050 is adjacentthe inferior of the two vertebrae, which may be done using the discreplacement holder 93. Then, using the four angled drill guide holes 99on the interface block 96 of the disc replacement holder 93, pilot holesmay be drilled into the superior and inferior vertebrae to aid in theinsertion of the first through fourth bone screws into the vertebrae. Asounding rod may be inserted through the drill guide holes 99 into thepilot holes.

Once the expandable disc replacement body 1012 is placed between the twoadjacent vertebrae, the first and second bone screws may be screwed intothe superior vertebra through the first and second openings 1038, 1040,respectively, and the third and fourth bone screws may be screwed intothe inferior vertebra through the third and fourth openings 1059, 1061,respectively.

After the first through fourth bone screws are in place, the expandabledisc replacement body 1012 is effectively locked between the twoadjacent vertebrae. At this point, the adjustment mechanism 1014 can beused to achieve various angles between the first wall 1018 and thesecond wall 1020 of the expandable disc replacement body 1012.

As first and second wedge translating screws 1084, 1089 are rotatedclockwise, they force the first and second wedges 1080, 1082 towards thedistal end 1023 of the expandable disc replacement body 1012. Due to thedistally directed movement of the lateral protrusion 1135 of the firstwedge 1080 in the first guide channel 1136 of the first wall 1018, thefirst wedge 1080 forces the first and second walls 1018, 1020 toseparate. Likewise, due to the distally directed movement of the lateralprotrusion 1145 of the second wedge 1082 in the second guide channel1146 of the first wall 1018, the second wedge 1082 also forces the firstand second walls 1018, 1020 to separate. Because the first and secondwalls 1018, 1020 are coupled at the hinge 1021, this separationincreases an angle formed therebetween. As such, when the first andsecond wedge translating screws 1084, 1089 are rotated, the rotation cancorrelate to a predetermined change in the angle between the first andsecond walls 1018, 1020. This capability to change the angle between thefirst and second walls 1018, 1020 allows for the expandable discreplacement body 1012 to be used to counteract various degrees oflordosis of the spine. The first and second wedge translating screws1084, 1089 can include markings on the screw head wherein rotation ofthe screw head from one marking to the adjacent marking correlates witha predetermined change in the angle between the first and second walls1018, 1020. The first wedge 1080 and the second wedge 1082 can also beinserted unequal amounts to create a first adjustment angle between thefirst and second walls 1018, 1020 on one lateral side 1024 of theexpandable disc replacement body 1012, and a different second adjustmentangle between the first and second walls 1018, 1020 on the other lateralside 1024 of the expandable disc replacement body 1012. The differencebetween the first and second adjustment angles may create a slightlateral angle between the first and second walls 1018, 1020, which mayfurther be used to counteract scoliosis of the spine. In this case, thehinge 1021 may alternatively be formed of a pliable material couplingthe first and second walls 1018, 1020 to allow for biaxial rotation.

When the first and second wedge translating screws 1084, 1089 arerotated to their positions that correlate to a predetermined anglebetween the first and second walls 1018, 1020, locking rings 1201, 1211can effectively block the first and second wedge translating screws1084, 1089 from backing out. The locking ring 1201 includes a lower tab1202 that slidably engages the second wall 1020 in the channel 1132 ofthe second wall 1020. Thus, the locking ring 1201 can be held in alocking position in contact with the first wedge translating screw 1084blocking the first wedge translating screw 1084 from backing out. Thelocking ring 1201 can be moved into contact with the head of the firstwedge translating screw 1084 by pressing the locking ring 1201 towardthe first wedge translating screw 1084.

Likewise, locking ring 1211 includes a lower tab 1212 that slidablyengages the second wall 1020 in the channel 1146 of the second wall1020. When the second wedge translating screw 1089 is rotated to itsposition that correlates to a predetermined angle between the first andsecond walls 1018, 1020, the locking ring 1211 can be moved into contactwith the head of the second wedge translating screw 1089 by pressing thelocking ring 1211 toward the second wedge translating screw 1089.

Thus, the locking rings 1201, 1211 ride in front of the screw head asthe screw is moved freely until the final position of the expandabledisc replacement body 1012 is achieved. Once the final position isachieved, the locking rings 1201, 1211 can be pushed into place bytapping/hitting the locking rings 1201, 1211 with force. The lockingrings 1201, 1211 can include teeth. A design featuring numerous teethprovides the greatest freedom. The surgeon is not confined to lockingthe expandable disc replacement body 1012 at angles of integer value,nor is the surgeon confined to locking the expandable disc replacementbody 1012 at largely spaced intervals (i.e., 3.2, 3.4, 3.6, 3.8degrees), as a square or hex shaped head would imply. Alternatively, thescrew head could be modified to be a square, hex, or Torx (star) shape.The locking rings 1201, 1211 can be modified to match the shape of thescrew head, depending on the shape chosen.

Alternatively, as shown in FIGS. 28A-28B, an alternative locking ring1901 can effectively block the first wedge translating screw 1084 frombacking out. The locking ring 1901 includes a superior projection 1902that is inserted through a slot 1903 in a first wedge 1980. Theprojection 1902 can be bent upward where the projection 1902 extendsbeyond a distal end of the slot 1903 preventing the locking ring 1901from moving out of its intended position. The locking ring 1901 alsoincludes a lower tab 1907 that slidably engages the second wall 1020 inthe channel 1132 of the second wall 1020. Thus, the locking ring 1901can be held in a locking position in contact with the first wedgetranslating screw 1084 blocking the first wedge translating screw 1084from backing out. The locking ring 1901 would be positioned with thelocking ring 1901 spaced from the first wedge translating screw 1084 andthe projection 1901 bent upward as part of the manufacturing/assemblyprocess. The surgeon would receive the part as one assembly attached tothe first wedge 1080, eliminating the need for a free floating,additional piece. When the first wedge translating screw 1084 is rotatedto its position that correlates to a predetermined angle between thefirst and second walls 1018, 1020, the locking ring 1901 can be movedinto contact with the head of the first wedge translating screw 1084 bypressing the locking ring 1901 toward the first wedge translating screw1084. The projection 1902 can be bent further upward to lock the lockingring 1901 against the first wedge translating screw 1084 therebyblocking the first wedge translating screw 1084 from backing out.Likewise, a locking ring 1911, similar to locking ring 1901, can be usedin the same manner to blocking a second wedge translating screw 1089from backing out.

Thus, the locking rings 1901, 1911 ride in front of the screw head asthe screw is moved freely until the final position of the expandabledisc replacement body 1012 is achieved. Once the final position isachieved, the locking rings 1901, 1911 will be pushed into place bytapping/hitting the locking rings 1901, 1911 with force. The lockingrings 1901, 1911 can include teeth. A design featuring numerous teethprovides the greatest freedom. The surgeon is not confined to lockingthe expandable disc replacement body 1012 at angles of integer value,nor is the surgeon confined to locking the expandable disc replacementbody 1012 at largely spaced intervals (i.e., 3.2, 3.4, 3.6, 3.8degrees), as a square or hex shaped head would imply. Alternatively, thescrew head could be modified to be a square, hex, or Torx (star) shape.The locking rings 1901, 1911 can be modified to match the shape of thescrew head, depending on the shape chosen.

Alternatively, when the first and second wedge translating screws arerotated to their positions that correlate to a predetermined anglebetween the first and second walls 1018, 1020, locking plates caneffectively block the first and second wedge translating screws frombacking out. In the spinal fixation system 1810 of FIG. 29, a lockingplate 1301 is shown. The locking plate 1301 includes posts 1303 a, 1303b, 1303 c that are inserted through slots 1203 in a first wedge 1080 a.A fourth post is not shown in FIG. 29. The locking plate 1301 can beheld in a locking position in contact with the first wedge translatingscrew 1084 blocking the first wedge translating screw 1084 from backingout. The locking plate 1301 would be positioned with the locking plate1301 spaced from the first wedge translating screw 1084 (as shown inFIG. 29) as part of the manufacturing/assembly process. The surgeonwould receive the part as one assembly attached to the first wedge 1080a, eliminating the need for a free floating, additional piece. When thefirst wedge translating screw 1084 is rotated to its position thatcorrelates to a predetermined angle between the first and second walls1018, 1020, the locking plate 1301 can be moved into contact with thehead of the first wedge translating screw 1084 by pressing the lockingplate 1301 toward the first wedge translating screw 1084. The lockingplate 1301 is placed in contact with a screw head surface 1378 of thefirst wedge translating screw 1084 in a tight interference fit therebyblocking the first wedge translating screw 1084 from backing out. Theshape of the locking interference fit could feature teeth 1376, inaddition to a square, hex or Torx shaped head. A locking plate for thesecond wedge translating screw operates in the same manner as lockingplate 1301.

Thus, the invention provides spinal fixation systems, multi-level spinalfixation systems, and kits for spinal surgery. Furthermore, it will beappreciated by those skilled in the art that elements of the variousembodiments described herein can be used in conjunction to achievedesired results. The specific embodiments illustrated are exemplary andare not meant to be limiting. In this regard, the embodimentsillustrated herein may refer to use for anterior cervical spine surgery.However, the spinal fixation systems and methods of the presentdisclosure are useful over the entire spine. For example, the spinalfixation systems and methods of the present disclosure can be used atthe thoracic or lumbar spine. Furthermore, embodiments of this inventioncan be inserted via lateral entry as opposed to the anterior entryembodiments depicted in the figures. While the non-limiting embodimentsof the present disclosure show an anterior cervical device that isapplicable for all direct anterior use from C2 to S1 vertebrae, in thethoracic spine and lumbar spine, the spinal fixation systems of thepresent disclosure can be used as a lateral cage, that enters from theside and has the adjustment mechanism that can increase lordosis and/orcorrect coronal angulation (i.e., in scoliosis). Thus, the spinalfixation systems and methods of the present disclosure work beneficiallyfrom C2 to S1 vertebrae, with one difference being the scale of theexpandable disc replacement body of the spinal fixation system.

Additionally, prior to the insertion of any of the described spinalfixation systems, a computer templating system can take specificmeasurements from preoperative imaging to define the native dimensionsof the disc space (i.e., height, width, depth, and angulation betweenadjacent vertebrae) as well as global dimensions (i.e., height, depth,and angulation of a general spinal region). These dimensions can then beused to calculate a prescribed amount of correction (i.e., height and/orangulation degree) of each individual spinal fixation system, betweenmultiple pairs of adjacent vertebrae, to achieve a desired globaldeformity correction. This prescribed correction can be multi-planar forboth sagittal and coronal plane correction.

Although the present invention has been described in detail withreference to certain embodiments, one skilled in the art will appreciatethat the present invention can be practiced by other than the describedembodiments, which have been presented for purposes of illustration andnot of limitation. Therefore, the scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.

What is claimed is:
 1. A spinal fixation system comprising: anexpandable disc replacement body including a first wall, a second wall,a hinge connecting the first wall and the second wall, and a firstbone-screw receiving section at a proximal end of the first wall; and anadjustment mechanism positioned between the first wall and the secondwall, wherein an angle between the first wall and the second wall can becontinuously varied between a lower value of the angle and an uppervalue of the angle by movement of the adjustment mechanism.
 2. Thesystem of claim 1 wherein: the expandable disc replacement body includesa second bone-screw receiving section at a proximal end of the secondwall.
 3. The system of claim 1 wherein: the first bone-screw receivingsection has a first opening for receiving a first bone screw, the firstopening having a first longitudinal axis, and the first bone-screwreceiving section has a second opening for receiving a second bonescrew, the second opening having a second longitudinal axis and thefirst longitudinal axis and the second longitudinal axis diverge in adirection toward a distal end of the expandable disc replacement body.4. The system of claim 3 wherein: the first bone-screw receiving sectionhas a first recessed edge between the first opening and the secondopening.
 5. The system of claim 3 wherein: the first bone-screwreceiving section has a first grasping recess between the first openingand the second opening.
 6. The system of claim 2 wherein: the secondbone-screw receiving section has a third opening for receiving a thirdbone screw, the third opening having a third longitudinal axis and thesecond bone-screw receiving section has a fourth opening for receiving afourth bone screw, the fourth opening having a fourth longitudinal axisand the third longitudinal axis and the fourth longitudinal axis divergein a direction toward a distal end of the expandable disc replacementbody.
 7. The system of claim 1 wherein: the adjustment mechanismcomprises a first wedge which slidably engages the first and secondwalls.
 8. The system of claim 7 wherein: the first wedge includes afirst wedge screw aperture for receiving a first wedge translating screwwhich is threadably connected to a first internally threaded cylinderthat is directly coupled to the hinge of the expandable disc replacementbody.
 9. The system of claim 8 wherein, the first wedge screw apertureincludes a first wedge snap ring recess containing a first wedge snapring.
 10. The system of claim 9 wherein, when the first wedgetranslating screw is received within the first wedge screw aperture, thefirst wedge snap ring expands into the first wedge snap ring recess toallow entry of the first wedge translating screw and once the firstwedge translating screw passes the first wedge snap ring, the firstwedge snap ring contracts, effectively blocking the first wedgetranslating screw from backing out.
 11. The system of claim 8 wherein:when the first wedge translating screw is rotated, the rotationcorrelates to a predetermined change in the angle between the first andsecond walls.
 12. The system of claim 7 wherein: the adjustmentmechanism further comprises a second wedge which slidably engages thefirst and second walls.
 13. The system of claim 12 wherein: the firstwedge and the second wedge can be inserted in unequal amounts to make afirst adjustment angle between the first wall and the second wall on onelateral side of the expandable disc replacement body different than asecond adjustment angle between the first wall and the second wall onanother lateral side of the expandable disc replacement body.
 14. Thesystem of claim 1 further comprising: an anterior plate cover which isdetachably coupled to the proximal end of the first wall.
 15. The systemof claim 5 further comprising: a disc replacement holder including fourangled drill guide holes and a grasping mechanism which detachablycouples to the grasping recess of the first wall.
 16. The system ofclaim 3 wherein: the first opening includes a first snap ring recesscontaining a first snap ring, and the second opening includes a secondsnap ring recess containing a second snap ring.
 17. The system of claim16 wherein: when the first bone screw is received within the firstopening, the first snap ring expands into the first snap ring recess toallow entry of the first bone screw and once the first bone screw passesthe first snap ring, the first snap ring contracts, effectively blockingthe first bone screw from backing out, and when the second bone screw isreceived within the second opening, the second snap ring expands intothe second snap ring recess to allow entry of the second bone screw andonce the second bone screw passes the second snap ring, the second snapring contracts, effectively blocking the second bone screw from backingout.
 18. The system of claim 6 wherein: the third opening includes athird snap ring recess containing a third snap ring, and the fourthopening includes a fourth snap ring recess containing a fourth snapring.
 19. The system of claim 18 wherein: when the third bone screw isreceived within the third opening, the third snap ring expands into thethird snap ring recess to allow entry of the third bone screw and oncethe third bone screw passes the third snap ring, the third snap ringcontracts, effectively blocking the third bone screw from backing out,and when the fourth bone screw is received within the fourth opening,the fourth snap ring expands into the fourth snap ring recess to allowentry of the fourth bone screw and once the fourth bone screw passes thefourth snap ring, the fourth snap ring contracts, effectively blockingthe fourth bone screw from backing out.
 20. The system of claim 1wherein: the first wall has a first space to allow for insertion of bonegraft, and the second wall has a second space to allow for insertion ofbone graft.
 21. The system of claim 1 wherein: the hinge is formed by apliable material coupling the first wall and the second wall.
 22. Thesystem of claim 1 wherein: the adjustment mechanism comprises a scissorjack which engages the first and second walls.
 23. The system of claim 1wherein: the adjustment mechanism comprises a scissor jack having aanteriorly accessible lead screw, and when the lead screw is rotated,the rotation correlates to a predetermined change in the angle betweenthe first and second walls.
 24. The system of claim 1 wherein: theadjustment mechanism comprises a scissor jack having a posteriorlyaccessible lead screw, and when the lead screw is rotated, the rotationcorrelates to a predetermined change in the angle between the first andsecond walls.
 25. The system of claim 24 wherein: the first wall and thesecond wall each include a fixation anchor for engaging a vertebra. 26.The system of claim 1 wherein: the adjustment mechanism comprises afeedback device for indicating an increment of movement of theadjustment mechanism.
 27. The system of claim 26 wherein: the feedbackdevice is a tactile device.
 28. The system of claim 26 wherein: thefeedback device is a display device.
 29. The system of claim 1 wherein:at least one of the first wall and the second wall includes a contouredbone engaging surface.
 30. The system of claim 1 wherein: at least oneof the first wall and the second wall includes perforations.
 31. Thesystem of claim 1 wherein: the hinge comprises a pair of arcuatestructures, a pair of cylindrical structures, one of the pair of arcuatestructures surrounding one of the pair of cylindrical structures, theother of pair of arcuate structures surrounding the other of the pair ofcylindrical structures, the pair of arcuate structures is connected toat least one of the first wall and the second wall, and the pair ofcylindrical structures is connected to the other of the first wall andthe second wall.
 32. The system of claim 31 wherein: an arcuate lengthof at least one of the pair of arcuate structures is used to limit theupper value of the angle by contacting one of the first wall and thesecond wall.
 33. The system of claim 31 wherein: the first wall has afirst space to allow for insertion of bone graft, and the hingecomprises a bar connecting the pair of arcuate structures or the pair ofcylindrical structures.
 34. The system of claim 33 wherein: the bar isconvex on a side facing the first space.
 35. The system of claim 1wherein: the adjustment mechanism comprises a first wedge which slidablyengages the first and second walls, at least one of the first wall andthe second wall includes a channel, and the first wedge includes aprotrusion which extends into and is movable in the channel.
 36. Thesystem of claim 35 wherein: motion of the first wedge is along an axisparallel to the second wall.
 37. The system of claim 31 wherein: theadjustment mechanism comprises a first wedge which slidably engages thefirst and second walls and a second wedge which slidably engages thefirst and second walls, one of the first wall and the second wallincludes a pair of channels, the first wedge includes a protrusion whichextends into and is movable in one of the pair of channels, and thesecond wedge includes a protrusion which extends into and is movable inthe other of the pair of channels.
 38. The system of claim 37 wherein:the first wedge and the second wedge are located at opposites sides ofthe first and second walls.
 39. The system of claim 35 wherein: theadjustment mechanism includes at least one threaded fastener in contactwith threads in at least one of the first wall, second wall, the hinge,or the first wedge.
 40. The system of claim 31 wherein: the adjustmentmechanism comprises a first wedge which slidably engages the first andsecond walls, the adjustment mechanism includes a threaded fastenerthreadably connected to an internally threaded hole of one of the pairof cylindrical structures.
 41. The system of claim 31 wherein: theadjustment mechanism includes two threaded fasteners which can beinserted in unequal amounts to make a first adjustment angle between thefirst wall and the second wall on one lateral side of the expandabledisc replacement body different than a second adjustment angle betweenthe first wall and the second wall on another lateral side of theexpandable disc replacement body.
 42. The system of claim 1 wherein: theadjustment mechanism includes a locking component which prevents theadjustment mechanism from changing the angle between the first wall andthe second wall when activated.
 43. The system of claim 42 wherein: thelocking component comprises a locking bar contacting the expandable discreplacement body which can be inserted into the adjustment mechanism inorder to prevent further rotational motion.
 44. The system of claim 42wherein: the locking component comprises a locking cap contacting theexpandable disc replacement body which surrounds the locking mechanismin order to prevent further rotational motion.
 45. The system of claim44 wherein: the locking cap comprises at least one of teeth, one or moreinsertable posts, one or more insertable spades, a square cover, a hexcover, or a torx cover for contacting the locking mechanism.
 46. Aspinal fixation system comprising: a disc replacement body including afirst wall and a second wall; a plate including a pair of opposedflanges and a first bone-screw receiving section at a superior end ofthe plate, wherein the opposed flanges are dimensioned to limitrotational movement of the disc replacement body when the plate iscoupled to the disc replacement body.
 47. The system of claim 46wherein: the plate further includes a second bone-screw receivingsection at an inferior end of the plate.
 48. The system of claim 46wherein: the first wall and the second wall are angled such that a firstdistance between the first wall and the second wall at a proximal end islarger than a second distance between the first wall and the second wallat a distal end.
 49. The system of claim 46 wherein: the first wall hasa first space to allow for insertion of bone graft, and the second wallhas a second space to allow for insertion of bone graft.
 50. The systemof claim 46 wherein: the first bone-screw receiving section has a firstopening for receiving a first bone screw, the first opening having afirst longitudinal axis, and the first bone-screw receiving section hasa second opening for receiving a second bone screw, the second openinghaving a second longitudinal axis and the first longitudinal axis andthe second longitudinal axis diverge in a direction toward a distal endof the disc replacement body.
 51. The system of claim 47 wherein: thesecond bone-screw receiving section has a third opening for receiving athird bone screw, the third opening having a third longitudinal axis,and the second bone-screw receiving section has a fourth opening forreceiving a fourth bone screw, the fourth opening having a fourthlongitudinal axis and the third longitudinal axis and the fourthlongitudinal axis diverge in a direction toward a distal end of the discreplacement body.
 52. The system of claim 51 wherein: the firstbone-screw receiving section has a first recessed edge between the firstopening and the second opening, and the second bone-screw receivingsection has a second recessed edge between the third opening and thefourth opening.
 53. The system of claim 46 wherein: the plate is coupledto the disc replacement body by a screw located centrally on the platesuch that the plate is coupled to a proximal end of the disc replacementbody.
 54. The system of claim 46 wherein: the pair of opposed flangesare movable flanges, such that they can move towards each other andapart from one another.
 55. The system of claim 54 wherein: the plate iscoupled to the disc replacement body by the movable flanges of the plategrasping the disc replacement body such that the plate is coupled to aproximal end of the disc replacement body.
 56. A spinal fixation systemcomprising: a disc replacement body portion including a first wall and asecond wall; and an plate portion including a first bone-screw receivingsection at a superior end of the plate portion, and a second bone-screwreceiving section at an inferior end of the plate portion, wherein thedisc replacement body portion and the plate portion are a unitarycomponent and are comprised of a material continuously forming the discreplacement body portion and the plate portion.
 57. The system of claim56 wherein: the first bone-screw receiving section has a first openingfor receiving a first bone screw, the first opening having a firstlongitudinal axis, and the first bone-screw receiving section has asecond opening for receiving a second bone screw, the second openinghaving a second longitudinal axis and the first longitudinal axis andthe second longitudinal axis diverge in a direction toward a distal endof the disc replacement body portion.
 58. The system of claim 56wherein: the second bone-screw receiving section has a third opening forreceiving a third bone screw, the third opening having a thirdlongitudinal axis, and the second bone-screw receiving section has afourth opening for receiving a fourth bone screw, the fourth openinghaving a fourth longitudinal axis and the third longitudinal axis andthe fourth longitudinal axis diverge in a direction toward a distal endof the disc replacement body portion.
 59. The system of claim 58wherein: the first bone-screw receiving section has a first recessededge between the first opening and the second opening, and the secondbone-screw receiving section has a second recessed edge between thethird opening and the fourth opening.
 60. The system of claim 56wherein: the first wall has a first space to allow for insertion of bonegraft, and the second wall has a second space to allow for insertion ofbone graft.
 61. The system of claim 56 wherein: the first wall and thesecond wall are angled such that a first distance between the first walland the second wall at a proximal end is larger than a second distancebetween the first wall and the second wall at a distal end.
 62. Thesystem of claim 56 further comprising: a wing having a stowed positionin which the wing is within a perimeter of the disc replacement bodyportion and having a deployed position in which the wing extends beyondthe perimeter.
 63. The system of claim 62 further comprising: a secondwing having a stowed position in which the second wing is within aperimeter of the disc replacement body portion and having a deployedposition in which the second wing extends beyond the perimeter.
 64. Aspinal fixation system comprising: a disc replacement body including afirst wall, a second wall, a joint connecting the first wall and thesecond wall; and an adjustment mechanism positioned between the firstwall and the second wall, wherein an angle between the first wall andthe second wall can be varied by movement of the adjustment mechanism.65. The system of claim 64 wherein: the joint is a ball joint.
 66. Thesystem of claim 64 further comprising: a plurality of additionaladjustment mechanisms positioned between the first wall and the secondwall, wherein an angle between the first wall and the second wall can bevaried by movement of each additional adjustment mechanism.
 67. Thesystem of claim 64 wherein: the adjustment mechanism and each additionaladjustment mechanism are located at corners of the disc replacementbody.
 68. The system of claim 64 wherein: the adjustment mechanism andeach additional adjustment mechanism provide multi-planar disc spacecorrection.
 69. A multi-level spinal fixation system comprising: a firstspinal fixation system according to claim 1; a second spinal fixationsystem according to claim 1; and a clamp dimensioned to couple togetherthe first spinal fixation system according to claim 1 and the secondspinal fixation system according to claim 1 when the first spinalfixation system according to claim 1 and the second spinal fixationsystem according to claim 1 are implanted in different intervertebraldisc spaces.
 70. A multi-level spinal fixation system comprising: afirst spinal fixation system according to claim 46; a second spinalfixation system according to claim 46; and a clamp dimensioned to coupletogether the first spinal fixation system according to claim 46 and thesecond spinal fixation system according to claim 46 when the firstspinal fixation system according to claim 46 and the second spinalfixation system according to claim 46 are implanted in differentintervertebral disc spaces.
 71. A multi-level spinal fixation systemcomprising: a first spinal fixation system according to claim 56; asecond spinal fixation system according to claim 56; and a clampdimensioned to couple together the first spinal fixation systemaccording to claim 56 and the second spinal fixation system according toclaim 56 when the first spinal fixation system according to claim 56 andthe second spinal fixation system according to claim 56 are implanted indifferent intervertebral disc spaces.
 72. A multi-level spinal fixationsystem comprising: a first spinal fixation system according to claim 64;a second spinal fixation system according to claim 64; and a clampdimensioned to couple together the first spinal fixation systemaccording to claim 64 and the second spinal fixation system according toclaim 64 when the first spinal fixation system according to claim 64 andthe second spinal fixation system according to claim 64 are implanted indifferent intervertebral disc spaces.
 73. The multi-level spinalfixation system of any of claims 69 to 72 wherein: the clamp includes anelliptical perimeter and an elongated slot, the clamp spatially fixingthe first spinal fixation system relative to the second spinal fixationsystem.
 74. A kit for spinal surgery, the kit comprising: a plurality ofdisc replacement trial components, each of the disc replacement trialcomponents comprising a body including a first wall and a second wall,and a plate section including a first bone-screw drill guide section ata superior end of the plate section, and a second bone-screw drill guidesection at an inferior end of the plate section, wherein a first body ofa first disc replacement trial component of the plurality of discreplacement trial components and a second body of a second discreplacement trial component of the plurality of disc replacement trialcomponents have different exterior dimensions.
 75. The kit of claim 74further comprising: a detachable handle configured to engage any of theplurality of disc replacement trial components.
 76. The kit of claim 75wherein: wherein a first angle between the first wall and the secondwall of the first disc replacement trial component is different than asecond angle between the first wall and the second wall of the seconddisc replacement trial component.
 77. A method for fixing adjacentvertebrae in a spine, the method comprising: (a) obtaining a medicalimage of the spine; (b) defining native dimensions of a disc space ofthe spine from the medical image; (c) determining corrected dimensionsfor the disc space of the spine; (d) inserting a spinal fixation systemaccording to claim 1 in the disc space of the spine; and (e) adjustingthe angle between the first wall and the second wall by movement of theadjustment mechanism such that the disc space of the spine correspondsto the corrected dimensions.